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diff --git a/include/llvm/IR/Use.h b/include/llvm/IR/Use.h
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+++ b/include/llvm/IR/Use.h
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+//===-- llvm/Use.h - Definition of the Use class ----------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This defines the Use class.  The Use class represents the operand of an
+// instruction or some other User instance which refers to a Value.  The Use
+// class keeps the "use list" of the referenced value up to date.
+//
+// Pointer tagging is used to efficiently find the User corresponding
+// to a Use without having to store a User pointer in every Use. A
+// User is preceded in memory by all the Uses corresponding to its
+// operands, and the low bits of one of the fields (Prev) of the Use
+// class are used to encode offsets to be able to find that User given
+// a pointer to any Use. For details, see:
+//
+//   http://www.llvm.org/docs/ProgrammersManual.html#UserLayout
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_USE_H
+#define LLVM_USE_H
+
+#include "llvm/ADT/PointerIntPair.h"
+#include "llvm/Support/Compiler.h"
+#include <cstddef>
+#include <iterator>
+
+namespace llvm {
+
+class Value;
+class User;
+class Use;
+template<typename>
+struct simplify_type;
+
+// Use** is only 4-byte aligned.
+template<>
+class PointerLikeTypeTraits<Use**> {
+public:
+  static inline void *getAsVoidPointer(Use** P) { return P; }
+  static inline Use **getFromVoidPointer(void *P) {
+    return static_cast<Use**>(P);
+  }
+  enum { NumLowBitsAvailable = 2 };
+};
+
+//===----------------------------------------------------------------------===//
+//                                  Use Class
+//===----------------------------------------------------------------------===//
+
+/// Use is here to make keeping the "use" list of a Value up-to-date really
+/// easy.
+class Use {
+public:
+  /// swap - provide a fast substitute to std::swap<Use>
+  /// that also works with less standard-compliant compilers
+  void swap(Use &RHS);
+
+  // A type for the word following an array of hung-off Uses in memory, which is
+  // a pointer back to their User with the bottom bit set.
+  typedef PointerIntPair<User*, 1, unsigned> UserRef;
+
+private:
+  /// Copy ctor - do not implement
+  Use(const Use &U) LLVM_DELETED_FUNCTION;
+
+  /// Destructor - Only for zap()
+  ~Use() {
+    if (Val) removeFromList();
+  }
+
+  enum PrevPtrTag { zeroDigitTag
+                  , oneDigitTag
+                  , stopTag
+                  , fullStopTag };
+
+  /// Constructor
+  Use(PrevPtrTag tag) : Val(0) {
+    Prev.setInt(tag);
+  }
+
+public:
+  /// Normally Use will just implicitly convert to a Value* that it holds.
+  operator Value*() const { return Val; }
+  
+  /// If implicit conversion to Value* doesn't work, the get() method returns
+  /// the Value*.
+  Value *get() const { return Val; }
+  
+  /// getUser - This returns the User that contains this Use.  For an
+  /// instruction operand, for example, this will return the instruction.
+  User *getUser() const;
+
+  inline void set(Value *Val);
+
+  Value *operator=(Value *RHS) {
+    set(RHS);
+    return RHS;
+  }
+  const Use &operator=(const Use &RHS) {
+    set(RHS.Val);
+    return *this;
+  }
+
+        Value *operator->()       { return Val; }
+  const Value *operator->() const { return Val; }
+
+  Use *getNext() const { return Next; }
+
+  
+  /// initTags - initialize the waymarking tags on an array of Uses, so that
+  /// getUser() can find the User from any of those Uses.
+  static Use *initTags(Use *Start, Use *Stop);
+
+  /// zap - This is used to destroy Use operands when the number of operands of
+  /// a User changes.
+  static void zap(Use *Start, const Use *Stop, bool del = false);
+
+private:
+  const Use* getImpliedUser() const;
+  
+  Value *Val;
+  Use *Next;
+  PointerIntPair<Use**, 2, PrevPtrTag> Prev;
+
+  void setPrev(Use **NewPrev) {
+    Prev.setPointer(NewPrev);
+  }
+  void addToList(Use **List) {
+    Next = *List;
+    if (Next) Next->setPrev(&Next);
+    setPrev(List);
+    *List = this;
+  }
+  void removeFromList() {
+    Use **StrippedPrev = Prev.getPointer();
+    *StrippedPrev = Next;
+    if (Next) Next->setPrev(StrippedPrev);
+  }
+
+  friend class Value;
+};
+
+// simplify_type - Allow clients to treat uses just like values when using
+// casting operators.
+template<> struct simplify_type<Use> {
+  typedef Value* SimpleType;
+  static SimpleType getSimplifiedValue(const Use &Val) {
+    return static_cast<SimpleType>(Val.get());
+  }
+};
+template<> struct simplify_type<const Use> {
+  typedef Value* SimpleType;
+  static SimpleType getSimplifiedValue(const Use &Val) {
+    return static_cast<SimpleType>(Val.get());
+  }
+};
+
+
+
+template<typename UserTy>  // UserTy == 'User' or 'const User'
+class value_use_iterator : public std::iterator<std::forward_iterator_tag,
+                                                UserTy*, ptrdiff_t> {
+  typedef std::iterator<std::forward_iterator_tag, UserTy*, ptrdiff_t> super;
+  typedef value_use_iterator<UserTy> _Self;
+
+  Use *U;
+  explicit value_use_iterator(Use *u) : U(u) {}
+  friend class Value;
+public:
+  typedef typename super::reference reference;
+  typedef typename super::pointer pointer;
+
+  value_use_iterator(const _Self &I) : U(I.U) {}
+  value_use_iterator() {}
+
+  bool operator==(const _Self &x) const {
+    return U == x.U;
+  }
+  bool operator!=(const _Self &x) const {
+    return !operator==(x);
+  }
+
+  /// atEnd - return true if this iterator is equal to use_end() on the value.
+  bool atEnd() const { return U == 0; }
+
+  // Iterator traversal: forward iteration only
+  _Self &operator++() {          // Preincrement
+    assert(U && "Cannot increment end iterator!");
+    U = U->getNext();
+    return *this;
+  }
+  _Self operator++(int) {        // Postincrement
+    _Self tmp = *this; ++*this; return tmp;
+  }
+
+  // Retrieve a pointer to the current User.
+  UserTy *operator*() const {
+    assert(U && "Cannot dereference end iterator!");
+    return U->getUser();
+  }
+
+  UserTy *operator->() const { return operator*(); }
+
+  Use &getUse() const { return *U; }
+  
+  /// getOperandNo - Return the operand # of this use in its User.  Defined in
+  /// User.h
+  ///
+  unsigned getOperandNo() const;
+};
+
+} // End llvm namespace
+
+#endif