Index: include/clang/Analysis/DefUse.h
===================================================================
--- /dev/null
+++ include/clang/Analysis/DefUse.h
@@ -0,0 +1,255 @@
+//===-- clang/Analysis/DefUse.h - DefUse analysis -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the declaration of DefUse analysis headers
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_DEFUSE_H
+#define LLVM_CLANG_DEFUSE_H
+
+#include "llvm/ADT/DenseMap.h"
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/AST/StmtVisitor.h"
+
+namespace clang {
+
+// forward definitions
+class CFG;
+class CFGBlock;
+
+class DefUse;
+
+namespace defuse {
+//===------------------------- DefUseNode -------------------------===//
+// Keeps the information for a particular 'definition' or 'use' of a variable
+// The structure is needed because a defuse chain can contains variable declarations
+// as well as variable reference. As a DeclStmt can contains several declarations
+// to address a particular variable we need to store its VarDecl or DeclRefExp
+class DefUseNode {
+public:
+  enum NodeKind {
+    VarDecl, VarRef
+  };
+  enum UseKind {
+    Use, Def, UseDef
+  };
+
+  DefUseNode(clang::VarDecl const* decl) :
+    var_decl(decl), kind(VarDecl), usage(Def) {
+  }
+  DefUseNode(DeclRefExpr const* ref, UseKind u = Use) :
+    var_ref(ref), kind(VarRef), usage(u) {
+  }
+
+  clang::VarDecl const* getDecl() const;
+
+  NodeKind const& getKind() const {
+    return kind;
+  }
+  UseKind const& getUse() const {
+    return usage;
+  }
+
+  clang::VarDecl const* getVarDecl() const {
+    assert(kind==VarDecl);
+    return var_decl;
+  }
+  DeclRefExpr const* getVarRef() const {
+    assert(kind==VarRef);
+    return var_ref;
+  }
+
+  bool operator==(DefUseNode const& n) const;
+
+private:
+  // a def-use node can be either a VarDecl or a DeclRefExpr
+  union {
+    clang::VarDecl const* var_decl;
+    DeclRefExpr const* var_ref;
+  };
+  NodeKind kind;
+  UseKind usage;
+};
+
+//===------------------------- Typedefs -------------------------===//
+class DefUseBlock;
+class VarDeclMap;
+typedef std::vector<DefUseBlock> DefUseData;
+typedef llvm::DenseMap<Stmt const*, unsigned> VarRefBlockMap;
+typedef std::vector<DefUseNode> DefUseVect;
+typedef std::vector<DefUseNode const*> VarRefsVect;
+
+//===------------------------- DefUseHelper -------------------------===//
+
+class DefUseHelper : public StmtVisitor<DefUseHelper> {
+  struct DefUseHelperImpl;
+  DefUseHelperImpl* pimpl;
+
+  void InitializeValues(DefUseData* data, VarRefBlockMap* bm, VarDeclMap* dm);
+
+  friend class clang::DefUse;
+public:
+  DefUseNode::UseKind current_use;
+  DefUseHelper();
+
+  virtual void HandleDeclRefExpr(DeclRefExpr *DR); // remember to call the
+                              // super class implementation of the method
+  void HandleDeclStmt(DeclStmt *DS);
+
+  virtual void HandleBinaryOperator(BinaryOperator* B);
+  virtual void HandleConditionalOperator(ConditionalOperator* C);
+  virtual void HandleCallExpr(CallExpr* C);
+  virtual void HandleUnaryOperator(UnaryOperator* U);
+  virtual void HandleArraySubscriptExpr(ArraySubscriptExpr* AS);
+
+  void VisitDeclRefExpr(DeclRefExpr *DR) {
+    return HandleDeclRefExpr(DR);
+  }
+  void VisitDeclStmt(DeclStmt *DS) {
+    return HandleDeclStmt(DS);
+  }
+  void VisitBinaryOperator(BinaryOperator* B) {
+    return HandleBinaryOperator(B);
+  }
+  void VisitConditionalOperator(ConditionalOperator* C) {
+    return HandleConditionalOperator(C);
+  }
+  void VisitCallExpr(CallExpr* C) {
+    return HandleCallExpr(C);
+  }
+  void VisitUnaryOperator(UnaryOperator* U) {
+    return HandleUnaryOperator(U);
+  }
+  void VisitArraySubscriptExpr(ArraySubscriptExpr* AS) {
+    return HandleArraySubscriptExpr(AS);
+  }
+
+  void VisitCFGBlock(clang::CFGBlock const& blk, CFGBlock const& entry);
+  void VisitStmt(Stmt* S);
+
+  virtual ~DefUseHelper();
+};
+
+void PrintVarDefs(DefUse const* DU, DeclRefExpr const* DR, ASTContext& ctx,
+    llvm::raw_ostream& out);
+void PrintVarUses(DefUse const* DU, DeclRefExpr const* DR, ASTContext& ctx,
+    llvm::raw_ostream& out);
+void PrintVarUses(DefUse const* DU, VarDecl const* VD, ASTContext& ctx,
+    llvm::raw_ostream& out);
+
+ASTConsumer* CreateDefUseTestConsumer(llvm::raw_ostream& out);
+
+} // end namespace defuse
+
+//===------------------------- DefUse -------------------------===//
+
+class DefUse {
+  ASTContext const& ctx;
+  defuse::DefUseData const* analysis_data;
+  defuse::VarDeclMap const* decl_map;
+  defuse::VarRefBlockMap const* block_map;
+  unsigned const num_cfg_blocks;
+
+  DefUse(ASTContext const& ctx_,
+      defuse::DefUseData const* analysis_data_,
+      defuse::VarDeclMap const* decl_map_,
+      defuse::VarRefBlockMap const* block_map_,
+      unsigned num_blocks) :
+    ctx(ctx_), analysis_data(analysis_data_), decl_map(decl_map_),
+    block_map(block_map_), num_cfg_blocks(num_blocks) {
+  }
+
+  bool isDef(defuse::DefUseNode const& n) const;
+
+  class iterator_impl {
+  public:
+    DefUse const* du;
+    defuse::DefUseNode const* node;
+
+    struct iter {
+      int block_id;
+      defuse::DefUseVect::const_iterator block_it;
+      iter(int blk_id) :
+        block_id(blk_id) {
+      }
+    };
+    iterator_impl() : du(NULL) { }
+    iterator_impl(DefUse const* du_) : du(du_) { }
+    iterator_impl& operator++() {
+      return inc(false);
+    }
+    virtual iterator_impl& inc(bool) = 0;
+  };
+public:
+  class uses_iterator : public std::iterator<std::input_iterator_tag,
+    DeclRefExpr, std::ptrdiff_t, DeclRefExpr const*>,
+    public iterator_impl {
+    iter iter_ptr;
+    bool inDefBlock;
+
+    uses_iterator() :
+      iterator_impl(), iter_ptr(-1), inDefBlock(true) { }
+    uses_iterator(DefUse const* du, defuse::DefUseNode const& n);
+    uses_iterator& inc(bool first);
+    friend class DefUse;
+  public:
+    bool operator!=(uses_iterator const& iter);
+    DeclRefExpr const* operator*();
+  };
+
+  class defs_iterator : public std::iterator<std::input_iterator_tag,
+  defuse::DefUseNode, std::ptrdiff_t, defuse::DefUseNode const*>,
+  public iterator_impl {
+    struct iter_ : public iter {
+      defuse::VarRefsVect::const_iterator reaches_it;
+      iter_(int blk_id) :
+        iter(blk_id) { }
+    } iter_ptr;
+    bool blockDef;
+
+    defs_iterator() :
+      iterator_impl(), iter_ptr(-1), blockDef(false) { }
+    defs_iterator(DefUse const* du, DeclRefExpr const& n);
+    defs_iterator& inc(bool first);
+    friend class DefUse;
+  public:
+    bool operator!=(defs_iterator const& iter);
+    defuse::DefUseNode const* operator*();
+  };
+
+  // USES //
+  defs_iterator defs_begin(DeclRefExpr const* var) const;
+  defs_iterator defs_end() const;
+
+  // DEFS //
+  uses_iterator uses_begin(DeclRefExpr const* var) const;
+  uses_iterator uses_begin(VarDecl const* var) const;
+  uses_iterator uses_end() const;
+
+  bool isUse(DeclRefExpr const* var) const;
+  bool isDef(DeclRefExpr const* var) const {
+    return isDef(defuse::DefUseNode(var, defuse::DefUseNode::Def));
+  }
+  bool isDef(VarDecl const* var) const {
+    return isDef(defuse::DefUseNode(var));
+  }
+
+  ~DefUse();
+
+  static DefUse* BuildDefUseChains(Stmt* body, ASTContext *ctx,
+      CFG* cfg, ParentMap* pm, defuse::DefUseHelper* helper = 0,
+      bool verbose = false, llvm::raw_ostream& out = llvm::outs());
+};
+
+} // end namespace clang
+
+#endif
Index: lib/Analysis/CMakeLists.txt
===================================================================
--- lib/Analysis/CMakeLists.txt
+++ lib/Analysis/CMakeLists.txt
@@ -13,6 +13,7 @@
   CocoaConventions.cpp
   Consumed.cpp
   CodeInjector.cpp
+  DefUse.cpp
   Dominators.cpp
   FormatString.cpp
   LiveVariables.cpp
Index: lib/Analysis/DefUse.cpp
===================================================================
--- /dev/null
+++ lib/Analysis/DefUse.cpp
@@ -0,0 +1,257 @@
+//===-- clang/Analysis/DefUse.h - DefUse analysis -------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file contains the declaration of DefUse analysis headers
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_DEFUSE_H
+#define LLVM_CLANG_DEFUSE_H
+
+#include "llvm/ADT/DenseMap.h"
+
+#include "clang/AST/ASTConsumer.h"
+#include "clang/AST/ParentMap.h"
+#include "clang/AST/StmtVisitor.h"
+
+namespace clang {
+
+// forward definitions
+class CFG;
+class CFGBlock;
+
+class DefUse;
+
+namespace defuse {
+//===------------------------- DefUseNode -------------------------===//
+// Keeps the information for a particular 'definition' or 'use' of a variable
+// The structure is needed because a defuse chain can contains variable declarations
+// as well as variable reference. As a DeclStmt can contains several declarations
+// to address a particular variable we need to store its VarDecl or DeclRefExp
+class DefUseNode {
+public:
+  enum NodeKind {
+    VarDecl, VarRef
+  };
+  enum UseKind {
+    Use, Def, UseDef
+  };
+
+  DefUseNode(clang::VarDecl const* decl) :
+    var_decl(decl), kind(VarDecl), usage(Def) {
+  }
+  DefUseNode(DeclRefExpr const* ref, UseKind u = Use) :
+    var_ref(ref), kind(VarRef), usage(u) {
+  }
+
+  clang::VarDecl const* getDecl() const;
+
+  NodeKind const& getKind() const {
+    return kind;
+  }
+  UseKind const& getUse() const {
+    return usage;
+  }
+
+  clang::VarDecl const* getVarDecl() const {
+    assert(kind==VarDecl);
+    return var_decl;
+  }
+  DeclRefExpr const* getVarRef() const {
+    assert(kind==VarRef);
+    return var_ref;
+  }
+
+  bool operator==(DefUseNode const& n) const;
+
+private:
+  // a def-use node can be either a VarDecl or a DeclRefExpr
+  union {
+    clang::VarDecl const* var_decl;
+    DeclRefExpr const* var_ref;
+  };
+  NodeKind kind;
+  UseKind usage;
+};
+
+//===------------------------- Typedefs -------------------------===//
+class DefUseBlock;
+class VarDeclMap;
+typedef std::vector<DefUseBlock> DefUseData;
+typedef llvm::DenseMap<Stmt const*, unsigned> VarRefBlockMap;
+typedef std::vector<DefUseNode> DefUseVect;
+typedef std::vector<DefUseNode const*> VarRefsVect;
+
+class DefUseHelper;
+
+//===------------------------- DefUseHelper -------------------------===//
+
+class DefUseHelper : public StmtVisitor<DefUseHelper> {
+  class DefUseHelperImpl;
+  DefUseHelperImpl* pimpl;
+
+  void InitializeValues(DefUseData* data, VarRefBlockMap* bm, VarDeclMap* dm);
+
+  friend class clang::DefUse;
+public:
+  DefUseNode::UseKind current_use;
+  DefUseHelper();
+
+  virtual void HandleDeclRefExpr(DeclRefExpr *DR); // remember to call the
+                              // super class implementation of the method
+  void HandleDeclStmt(DeclStmt *DS);
+
+  virtual void HandleBinaryOperator(BinaryOperator* B);
+  virtual void HandleConditionalOperator(ConditionalOperator* C);
+  virtual void HandleCallExpr(CallExpr* C);
+  virtual void HandleUnaryOperator(UnaryOperator* U);
+  virtual void HandleArraySubscriptExpr(ArraySubscriptExpr* AS);
+
+  void VisitDeclRefExpr(DeclRefExpr *DR) {
+    return HandleDeclRefExpr(DR);
+  }
+  void VisitDeclStmt(DeclStmt *DS) {
+    return HandleDeclStmt(DS);
+  }
+  void VisitBinaryOperator(BinaryOperator* B) {
+    return HandleBinaryOperator(B);
+  }
+  void VisitConditionalOperator(ConditionalOperator* C) {
+    return HandleConditionalOperator(C);
+  }
+  void VisitCallExpr(CallExpr* C) {
+    return HandleCallExpr(C);
+  }
+  void VisitUnaryOperator(UnaryOperator* U) {
+    return HandleUnaryOperator(U);
+  }
+  void VisitArraySubscriptExpr(ArraySubscriptExpr* AS) {
+    return HandleArraySubscriptExpr(AS);
+  }
+
+  void VisitCFGBlock(clang::CFGBlock const& blk, CFGBlock const& entry);
+  void VisitStmt(Stmt* S);
+
+  virtual ~DefUseHelper();
+};
+
+void PrintVarDefs(DefUse const* DU, DeclRefExpr const* DR, ASTContext& ctx,
+    llvm::raw_ostream& out);
+void PrintVarUses(DefUse const* DU, DeclRefExpr const* DR, ASTContext& ctx,
+    llvm::raw_ostream& out);
+void PrintVarUses(DefUse const* DU, VarDecl const* VD, ASTContext& ctx,
+    llvm::raw_ostream& out);
+
+ASTConsumer* CreateDefUseTestConsumer(llvm::raw_ostream& out);
+
+} // end namespace defuse
+
+//===------------------------- DefUse -------------------------===//
+
+class DefUse {
+  ASTContext const& ctx;
+  defuse::DefUseData const* analysis_data;
+  defuse::VarDeclMap const* decl_map;
+  defuse::VarRefBlockMap const* block_map;
+  unsigned const num_cfg_blocks;
+
+  DefUse(ASTContext const& ctx_,
+      defuse::DefUseData const* analysis_data_,
+      defuse::VarDeclMap const* decl_map_,
+      defuse::VarRefBlockMap const* block_map_,
+      unsigned num_blocks) :
+    ctx(ctx_), analysis_data(analysis_data_), decl_map(decl_map_),
+    block_map(block_map_), num_cfg_blocks(num_blocks) {
+  }
+
+  bool isDef(defuse::DefUseNode const& n) const;
+
+  class iterator_impl {
+  public:
+    DefUse const* du;
+    defuse::DefUseNode const* node;
+
+    struct iter {
+      int block_id;
+      defuse::DefUseVect::const_iterator block_it;
+      iter(int blk_id) :
+        block_id(blk_id) {
+      }
+    };
+    iterator_impl() : du(NULL) { }
+    iterator_impl(DefUse const* du_) : du(du_) { }
+    iterator_impl& operator++() {
+      return inc(false);
+    }
+    virtual iterator_impl& inc(bool) = 0;
+  };
+public:
+  class uses_iterator : public std::iterator<std::input_iterator_tag,
+    DeclRefExpr, std::ptrdiff_t, DeclRefExpr const*>,
+    public iterator_impl {
+    iter iter_ptr;
+    bool inDefBlock;
+
+    uses_iterator() :
+      iterator_impl(), iter_ptr(-1), inDefBlock(true) { }
+    uses_iterator(DefUse const* du, defuse::DefUseNode const& n);
+    uses_iterator& inc(bool first);
+    friend class DefUse;
+  public:
+    bool operator!=(uses_iterator const& iter);
+    DeclRefExpr const* operator*();
+  };
+
+  class defs_iterator : public std::iterator<std::input_iterator_tag,
+  defuse::DefUseNode, std::ptrdiff_t, defuse::DefUseNode const*>,
+  public iterator_impl {
+    struct iter_ : public iter {
+      defuse::VarRefsVect::const_iterator reaches_it;
+      iter_(int blk_id) :
+        iter(blk_id) { }
+    } iter_ptr;
+    bool blockDef;
+
+    defs_iterator() :
+      iterator_impl(), iter_ptr(-1), blockDef(false) { }
+    defs_iterator(DefUse const* du, DeclRefExpr const& n);
+    defs_iterator& inc(bool first);
+    friend class DefUse;
+  public:
+    bool operator!=(defs_iterator const& iter);
+    defuse::DefUseNode const* operator*();
+  };
+
+  // USES //
+  defs_iterator defs_begin(DeclRefExpr const* var) const;
+  defs_iterator defs_end() const;
+
+  // DEFS //
+  uses_iterator uses_begin(DeclRefExpr const* var) const;
+  uses_iterator uses_begin(VarDecl const* var) const;
+  uses_iterator uses_end() const;
+
+  bool isUse(DeclRefExpr const* var) const;
+  bool isDef(DeclRefExpr const* var) const {
+    return isDef(defuse::DefUseNode(var, defuse::DefUseNode::Def));
+  }
+  bool isDef(VarDecl const* var) const {
+    return isDef(defuse::DefUseNode(var));
+  }
+
+  ~DefUse();
+
+  static DefUse* BuildDefUseChains(Stmt* body, ASTContext *ctx,
+      CFG* cfg, ParentMap* pm, defuse::DefUseHelper* helper = 0,
+      bool verbose = false, llvm::raw_ostream& out = llvm::outs());
+};
+
+} // end namespace clang
+
+#endif