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+//===- llvm/Value.h - Definition of the Value class -------------*- C++ -*-===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is distributed under the University of Illinois Open Source
+// License. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+//
+// This file declares the Value class.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_IR_VALUE_H
+#define LLVM_IR_VALUE_H
+
+#include "llvm-c/Types.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/IR/Use.h"
+#include "llvm/Support/CBindingWrapping.h"
+#include "llvm/Support/Casting.h"
+#include <cassert>
+#include <iterator>
+#include <memory>
+
+namespace llvm {
+
+class APInt;
+class Argument;
+class BasicBlock;
+class Constant;
+class ConstantData;
+class ConstantAggregate;
+class DataLayout;
+class Function;
+class GlobalAlias;
+class GlobalIFunc;
+class GlobalIndirectSymbol;
+class GlobalObject;
+class GlobalValue;
+class GlobalVariable;
+class InlineAsm;
+class Instruction;
+class LLVMContext;
+class Module;
+class ModuleSlotTracker;
+class raw_ostream;
+template<typename ValueTy> class StringMapEntry;
+class StringRef;
+class Twine;
+class Type;
+class User;
+
+using ValueName = StringMapEntry<Value *>;
+
+//===----------------------------------------------------------------------===//
+//                                 Value Class
+//===----------------------------------------------------------------------===//
+
+/// \brief LLVM Value Representation
+///
+/// This is a very important LLVM class. It is the base class of all values
+/// computed by a program that may be used as operands to other values. Value is
+/// the super class of other important classes such as Instruction and Function.
+/// All Values have a Type. Type is not a subclass of Value. Some values can
+/// have a name and they belong to some Module.  Setting the name on the Value
+/// automatically updates the module's symbol table.
+///
+/// Every value has a "use list" that keeps track of which other Values are
+/// using this Value.  A Value can also have an arbitrary number of ValueHandle
+/// objects that watch it and listen to RAUW and Destroy events.  See
+/// llvm/IR/ValueHandle.h for details.
+class Value {
+  // The least-significant bit of the first word of Value *must* be zero:
+  //   http://www.llvm.org/docs/ProgrammersManual.html#the-waymarking-algorithm
+  Type *VTy;
+  Use *UseList;
+
+  friend class ValueAsMetadata; // Allow access to IsUsedByMD.
+  friend class ValueHandleBase;
+
+  const unsigned char SubclassID;   // Subclass identifier (for isa/dyn_cast)
+  unsigned char HasValueHandle : 1; // Has a ValueHandle pointing to this?
+
+protected:
+  /// \brief Hold subclass data that can be dropped.
+  ///
+  /// This member is similar to SubclassData, however it is for holding
+  /// information which may be used to aid optimization, but which may be
+  /// cleared to zero without affecting conservative interpretation.
+  unsigned char SubclassOptionalData : 7;
+
+private:
+  /// \brief Hold arbitrary subclass data.
+  ///
+  /// This member is defined by this class, but is not used for anything.
+  /// Subclasses can use it to hold whatever state they find useful.  This
+  /// field is initialized to zero by the ctor.
+  unsigned short SubclassData;
+
+protected:
+  /// \brief The number of operands in the subclass.
+  ///
+  /// This member is defined by this class, but not used for anything.
+  /// Subclasses can use it to store their number of operands, if they have
+  /// any.
+  ///
+  /// This is stored here to save space in User on 64-bit hosts.  Since most
+  /// instances of Value have operands, 32-bit hosts aren't significantly
+  /// affected.
+  ///
+  /// Note, this should *NOT* be used directly by any class other than User.
+  /// User uses this value to find the Use list.
+  enum : unsigned { NumUserOperandsBits = 28 };
+  unsigned NumUserOperands : NumUserOperandsBits;
+
+  // Use the same type as the bitfield above so that MSVC will pack them.
+  unsigned IsUsedByMD : 1;
+  unsigned HasName : 1;
+  unsigned HasHungOffUses : 1;
+  unsigned HasDescriptor : 1;
+
+private:
+  template <typename UseT> // UseT == 'Use' or 'const Use'
+  class use_iterator_impl
+      : public std::iterator<std::forward_iterator_tag, UseT *> {
+    friend class Value;
+
+    UseT *U;
+
+    explicit use_iterator_impl(UseT *u) : U(u) {}
+
+  public:
+    use_iterator_impl() : U() {}
+
+    bool operator==(const use_iterator_impl &x) const { return U == x.U; }
+    bool operator!=(const use_iterator_impl &x) const { return !operator==(x); }
+
+    use_iterator_impl &operator++() { // Preincrement
+      assert(U && "Cannot increment end iterator!");
+      U = U->getNext();
+      return *this;
+    }
+
+    use_iterator_impl operator++(int) { // Postincrement
+      auto tmp = *this;
+      ++*this;
+      return tmp;
+    }
+
+    UseT &operator*() const {
+      assert(U && "Cannot dereference end iterator!");
+      return *U;
+    }
+
+    UseT *operator->() const { return &operator*(); }
+
+    operator use_iterator_impl<const UseT>() const {
+      return use_iterator_impl<const UseT>(U);
+    }
+  };
+
+  template <typename UserTy> // UserTy == 'User' or 'const User'
+  class user_iterator_impl
+      : public std::iterator<std::forward_iterator_tag, UserTy *> {
+    use_iterator_impl<Use> UI;
+    explicit user_iterator_impl(Use *U) : UI(U) {}
+    friend class Value;
+
+  public:
+    user_iterator_impl() = default;
+
+    bool operator==(const user_iterator_impl &x) const { return UI == x.UI; }
+    bool operator!=(const user_iterator_impl &x) const { return !operator==(x); }
+
+    /// \brief Returns true if this iterator is equal to user_end() on the value.
+    bool atEnd() const { return *this == user_iterator_impl(); }
+
+    user_iterator_impl &operator++() { // Preincrement
+      ++UI;
+      return *this;
+    }
+
+    user_iterator_impl operator++(int) { // Postincrement
+      auto tmp = *this;
+      ++*this;
+      return tmp;
+    }
+
+    // Retrieve a pointer to the current User.
+    UserTy *operator*() const {
+      return UI->getUser();
+    }
+
+    UserTy *operator->() const { return operator*(); }
+
+    operator user_iterator_impl<const UserTy>() const {
+      return user_iterator_impl<const UserTy>(*UI);
+    }
+
+    Use &getUse() const { return *UI; }
+  };
+
+protected:
+  Value(Type *Ty, unsigned scid);
+
+  /// Value's destructor should be virtual by design, but that would require
+  /// that Value and all of its subclasses have a vtable that effectively
+  /// duplicates the information in the value ID. As a size optimization, the
+  /// destructor has been protected, and the caller should manually call
+  /// deleteValue.
+  ~Value(); // Use deleteValue() to delete a generic Value.
+
+public:
+  Value(const Value &) = delete;
+  Value &operator=(const Value &) = delete;
+
+  /// Delete a pointer to a generic Value.
+  void deleteValue();
+
+  /// \brief Support for debugging, callable in GDB: V->dump()
+  void dump() const;
+
+  /// \brief Implement operator<< on Value.
+  /// @{
+  void print(raw_ostream &O, bool IsForDebug = false) const;
+  void print(raw_ostream &O, ModuleSlotTracker &MST,
+             bool IsForDebug = false) const;
+  /// @}
+
+  /// \brief Print the name of this Value out to the specified raw_ostream.
+  ///
+  /// This is useful when you just want to print 'int %reg126', not the
+  /// instruction that generated it. If you specify a Module for context, then
+  /// even constanst get pretty-printed; for example, the type of a null
+  /// pointer is printed symbolically.
+  /// @{
+  void printAsOperand(raw_ostream &O, bool PrintType = true,
+                      const Module *M = nullptr) const;
+  void printAsOperand(raw_ostream &O, bool PrintType,
+                      ModuleSlotTracker &MST) const;
+  /// @}
+
+  /// \brief All values are typed, get the type of this value.
+  Type *getType() const { return VTy; }
+
+  /// \brief All values hold a context through their type.
+  LLVMContext &getContext() const;
+
+  // \brief All values can potentially be named.
+  bool hasName() const { return HasName; }
+  ValueName *getValueName() const;
+  void setValueName(ValueName *VN);
+
+private:
+  void destroyValueName();
+  void doRAUW(Value *New, bool NoMetadata);
+  void setNameImpl(const Twine &Name);
+
+public:
+  /// \brief Return a constant reference to the value's name.
+  ///
+  /// This guaranteed to return the same reference as long as the value is not
+  /// modified.  If the value has a name, this does a hashtable lookup, so it's
+  /// not free.
+  StringRef getName() const;
+
+  /// \brief Change the name of the value.
+  ///
+  /// Choose a new unique name if the provided name is taken.
+  ///
+  /// \param Name The new name; or "" if the value's name should be removed.
+  void setName(const Twine &Name);
+
+  /// \brief Transfer the name from V to this value.
+  ///
+  /// After taking V's name, sets V's name to empty.
+  ///
+  /// \note It is an error to call V->takeName(V).
+  void takeName(Value *V);
+
+  /// \brief Change all uses of this to point to a new Value.
+  ///
+  /// Go through the uses list for this definition and make each use point to
+  /// "V" instead of "this".  After this completes, 'this's use list is
+  /// guaranteed to be empty.
+  void replaceAllUsesWith(Value *V);
+
+  /// \brief Change non-metadata uses of this to point to a new Value.
+  ///
+  /// Go through the uses list for this definition and make each use point to
+  /// "V" instead of "this". This function skips metadata entries in the list.
+  void replaceNonMetadataUsesWith(Value *V);
+
+  /// replaceUsesOutsideBlock - Go through the uses list for this definition and
+  /// make each use point to "V" instead of "this" when the use is outside the
+  /// block. 'This's use list is expected to have at least one element.
+  /// Unlike replaceAllUsesWith this function does not support basic block
+  /// values or constant users.
+  void replaceUsesOutsideBlock(Value *V, BasicBlock *BB);
+
+  /// replaceUsesExceptBlockAddr - Go through the uses list for this definition
+  /// and make each use point to "V" instead of "this" when the use is outside
+  /// the block. 'This's use list is expected to have at least one element.
+  /// Unlike replaceAllUsesWith this function skips blockaddr uses.
+  void replaceUsesExceptBlockAddr(Value *New);
+
+  //----------------------------------------------------------------------
+  // Methods for handling the chain of uses of this Value.
+  //
+  // Materializing a function can introduce new uses, so these methods come in
+  // two variants:
+  // The methods that start with materialized_ check the uses that are
+  // currently known given which functions are materialized. Be very careful
+  // when using them since you might not get all uses.
+  // The methods that don't start with materialized_ assert that modules is
+  // fully materialized.
+  void assertModuleIsMaterializedImpl() const;
+  // This indirection exists so we can keep assertModuleIsMaterializedImpl()
+  // around in release builds of Value.cpp to be linked with other code built
+  // in debug mode. But this avoids calling it in any of the release built code.
+  void assertModuleIsMaterialized() const {
+#ifndef NDEBUG
+    assertModuleIsMaterializedImpl();
+#endif
+  }
+
+  bool use_empty() const {
+    assertModuleIsMaterialized();
+    return UseList == nullptr;
+  }
+
+  bool materialized_use_empty() const {
+    return UseList == nullptr;
+  }
+
+  using use_iterator = use_iterator_impl<Use>;
+  using const_use_iterator = use_iterator_impl<const Use>;
+
+  use_iterator materialized_use_begin() { return use_iterator(UseList); }
+  const_use_iterator materialized_use_begin() const {
+    return const_use_iterator(UseList);
+  }
+  use_iterator use_begin() {
+    assertModuleIsMaterialized();
+    return materialized_use_begin();
+  }
+  const_use_iterator use_begin() const {
+    assertModuleIsMaterialized();
+    return materialized_use_begin();
+  }
+  use_iterator use_end() { return use_iterator(); }
+  const_use_iterator use_end() const { return const_use_iterator(); }
+  iterator_range<use_iterator> materialized_uses() {
+    return make_range(materialized_use_begin(), use_end());
+  }
+  iterator_range<const_use_iterator> materialized_uses() const {
+    return make_range(materialized_use_begin(), use_end());
+  }
+  iterator_range<use_iterator> uses() {
+    assertModuleIsMaterialized();
+    return materialized_uses();
+  }
+  iterator_range<const_use_iterator> uses() const {
+    assertModuleIsMaterialized();
+    return materialized_uses();
+  }
+
+  bool user_empty() const {
+    assertModuleIsMaterialized();
+    return UseList == nullptr;
+  }
+
+  using user_iterator = user_iterator_impl<User>;
+  using const_user_iterator = user_iterator_impl<const User>;
+
+  user_iterator materialized_user_begin() { return user_iterator(UseList); }
+  const_user_iterator materialized_user_begin() const {
+    return const_user_iterator(UseList);
+  }
+  user_iterator user_begin() {
+    assertModuleIsMaterialized();
+    return materialized_user_begin();
+  }
+  const_user_iterator user_begin() const {
+    assertModuleIsMaterialized();
+    return materialized_user_begin();
+  }
+  user_iterator user_end() { return user_iterator(); }
+  const_user_iterator user_end() const { return const_user_iterator(); }
+  User *user_back() {
+    assertModuleIsMaterialized();
+    return *materialized_user_begin();
+  }
+  const User *user_back() const {
+    assertModuleIsMaterialized();
+    return *materialized_user_begin();
+  }
+  iterator_range<user_iterator> materialized_users() {
+    return make_range(materialized_user_begin(), user_end());
+  }
+  iterator_range<const_user_iterator> materialized_users() const {
+    return make_range(materialized_user_begin(), user_end());
+  }
+  iterator_range<user_iterator> users() {
+    assertModuleIsMaterialized();
+    return materialized_users();
+  }
+  iterator_range<const_user_iterator> users() const {
+    assertModuleIsMaterialized();
+    return materialized_users();
+  }
+
+  /// \brief Return true if there is exactly one user of this value.
+  ///
+  /// This is specialized because it is a common request and does not require
+  /// traversing the whole use list.
+  bool hasOneUse() const {
+    const_use_iterator I = use_begin(), E = use_end();
+    if (I == E) return false;
+    return ++I == E;
+  }
+
+  /// \brief Return true if this Value has exactly N users.
+  bool hasNUses(unsigned N) const;
+
+  /// \brief Return true if this value has N users or more.
+  ///
+  /// This is logically equivalent to getNumUses() >= N.
+  bool hasNUsesOrMore(unsigned N) const;
+
+  /// \brief Check if this value is used in the specified basic block.
+  bool isUsedInBasicBlock(const BasicBlock *BB) const;
+
+  /// \brief This method computes the number of uses of this Value.
+  ///
+  /// This is a linear time operation.  Use hasOneUse, hasNUses, or
+  /// hasNUsesOrMore to check for specific values.
+  unsigned getNumUses() const;
+
+  /// \brief This method should only be used by the Use class.
+  void addUse(Use &U) { U.addToList(&UseList); }
+
+  /// \brief Concrete subclass of this.
+  ///
+  /// An enumeration for keeping track of the concrete subclass of Value that
+  /// is actually instantiated. Values of this enumeration are kept in the
+  /// Value classes SubclassID field. They are used for concrete type
+  /// identification.
+  enum ValueTy {
+#define HANDLE_VALUE(Name) Name##Val,
+#include "llvm/IR/Value.def"
+
+    // Markers:
+#define HANDLE_CONSTANT_MARKER(Marker, Constant) Marker = Constant##Val,
+#include "llvm/IR/Value.def"
+  };
+
+  /// \brief Return an ID for the concrete type of this object.
+  ///
+  /// This is used to implement the classof checks.  This should not be used
+  /// for any other purpose, as the values may change as LLVM evolves.  Also,
+  /// note that for instructions, the Instruction's opcode is added to
+  /// InstructionVal. So this means three things:
+  /// # there is no value with code InstructionVal (no opcode==0).
+  /// # there are more possible values for the value type than in ValueTy enum.
+  /// # the InstructionVal enumerator must be the highest valued enumerator in
+  ///   the ValueTy enum.
+  unsigned getValueID() const {
+    return SubclassID;
+  }
+
+  /// \brief Return the raw optional flags value contained in this value.
+  ///
+  /// This should only be used when testing two Values for equivalence.
+  unsigned getRawSubclassOptionalData() const {
+    return SubclassOptionalData;
+  }
+
+  /// \brief Clear the optional flags contained in this value.
+  void clearSubclassOptionalData() {
+    SubclassOptionalData = 0;
+  }
+
+  /// \brief Check the optional flags for equality.
+  bool hasSameSubclassOptionalData(const Value *V) const {
+    return SubclassOptionalData == V->SubclassOptionalData;
+  }
+
+  /// \brief Return true if there is a value handle associated with this value.
+  bool hasValueHandle() const { return HasValueHandle; }
+
+  /// \brief Return true if there is metadata referencing this value.
+  bool isUsedByMetadata() const { return IsUsedByMD; }
+
+  /// \brief Return true if this value is a swifterror value.
+  ///
+  /// swifterror values can be either a function argument or an alloca with a
+  /// swifterror attribute.
+  bool isSwiftError() const;
+
+  /// \brief Strip off pointer casts, all-zero GEPs, and aliases.
+  ///
+  /// Returns the original uncasted value.  If this is called on a non-pointer
+  /// value, it returns 'this'.
+  const Value *stripPointerCasts() const;
+  Value *stripPointerCasts() {
+    return const_cast<Value *>(
+                         static_cast<const Value *>(this)->stripPointerCasts());
+  }
+
+  /// \brief Strip off pointer casts, all-zero GEPs, aliases and barriers.
+  ///
+  /// Returns the original uncasted value.  If this is called on a non-pointer
+  /// value, it returns 'this'. This function should be used only in
+  /// Alias analysis.
+  const Value *stripPointerCastsAndBarriers() const;
+  Value *stripPointerCastsAndBarriers() {
+    return const_cast<Value *>(
+        static_cast<const Value *>(this)->stripPointerCastsAndBarriers());
+  }
+
+  /// \brief Strip off pointer casts and all-zero GEPs.
+  ///
+  /// Returns the original uncasted value.  If this is called on a non-pointer
+  /// value, it returns 'this'.
+  const Value *stripPointerCastsNoFollowAliases() const;
+  Value *stripPointerCastsNoFollowAliases() {
+    return const_cast<Value *>(
+          static_cast<const Value *>(this)->stripPointerCastsNoFollowAliases());
+  }
+
+  /// \brief Strip off pointer casts and all-constant inbounds GEPs.
+  ///
+  /// Returns the original pointer value.  If this is called on a non-pointer
+  /// value, it returns 'this'.
+  const Value *stripInBoundsConstantOffsets() const;
+  Value *stripInBoundsConstantOffsets() {
+    return const_cast<Value *>(
+              static_cast<const Value *>(this)->stripInBoundsConstantOffsets());
+  }
+
+  /// \brief Accumulate offsets from \a stripInBoundsConstantOffsets().
+  ///
+  /// Stores the resulting constant offset stripped into the APInt provided.
+  /// The provided APInt will be extended or truncated as needed to be the
+  /// correct bitwidth for an offset of this pointer type.
+  ///
+  /// If this is called on a non-pointer value, it returns 'this'.
+  const Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
+                                                         APInt &Offset) const;
+  Value *stripAndAccumulateInBoundsConstantOffsets(const DataLayout &DL,
+                                                   APInt &Offset) {
+    return const_cast<Value *>(static_cast<const Value *>(this)
+        ->stripAndAccumulateInBoundsConstantOffsets(DL, Offset));
+  }
+
+  /// \brief Strip off pointer casts and inbounds GEPs.
+  ///
+  /// Returns the original pointer value.  If this is called on a non-pointer
+  /// value, it returns 'this'.
+  const Value *stripInBoundsOffsets() const;
+  Value *stripInBoundsOffsets() {
+    return const_cast<Value *>(
+                      static_cast<const Value *>(this)->stripInBoundsOffsets());
+  }
+
+  /// \brief Returns the number of bytes known to be dereferenceable for the
+  /// pointer value.
+  ///
+  /// If CanBeNull is set by this function the pointer can either be null or be
+  /// dereferenceable up to the returned number of bytes.
+  uint64_t getPointerDereferenceableBytes(const DataLayout &DL,
+                                          bool &CanBeNull) const;
+
+  /// \brief Returns an alignment of the pointer value.
+  ///
+  /// Returns an alignment which is either specified explicitly, e.g. via
+  /// align attribute of a function argument, or guaranteed by DataLayout.
+  unsigned getPointerAlignment(const DataLayout &DL) const;
+
+  /// \brief Translate PHI node to its predecessor from the given basic block.
+  ///
+  /// If this value is a PHI node with CurBB as its parent, return the value in
+  /// the PHI node corresponding to PredBB.  If not, return ourself.  This is
+  /// useful if you want to know the value something has in a predecessor
+  /// block.
+  const Value *DoPHITranslation(const BasicBlock *CurBB,
+                                const BasicBlock *PredBB) const;
+  Value *DoPHITranslation(const BasicBlock *CurBB, const BasicBlock *PredBB) {
+    return const_cast<Value *>(
+             static_cast<const Value *>(this)->DoPHITranslation(CurBB, PredBB));
+  }
+
+  /// \brief The maximum alignment for instructions.
+  ///
+  /// This is the greatest alignment value supported by load, store, and alloca
+  /// instructions, and global values.
+  static const unsigned MaxAlignmentExponent = 29;
+  static const unsigned MaximumAlignment = 1u << MaxAlignmentExponent;
+
+  /// \brief Mutate the type of this Value to be of the specified type.
+  ///
+  /// Note that this is an extremely dangerous operation which can create
+  /// completely invalid IR very easily.  It is strongly recommended that you
+  /// recreate IR objects with the right types instead of mutating them in
+  /// place.
+  void mutateType(Type *Ty) {
+    VTy = Ty;
+  }
+
+  /// \brief Sort the use-list.
+  ///
+  /// Sorts the Value's use-list by Cmp using a stable mergesort.  Cmp is
+  /// expected to compare two \a Use references.
+  template <class Compare> void sortUseList(Compare Cmp);
+
+  /// \brief Reverse the use-list.
+  void reverseUseList();
+
+private:
+  /// \brief Merge two lists together.
+  ///
+  /// Merges \c L and \c R using \c Cmp.  To enable stable sorts, always pushes
+  /// "equal" items from L before items from R.
+  ///
+  /// \return the first element in the list.
+  ///
+  /// \note Completely ignores \a Use::Prev (doesn't read, doesn't update).
+  template <class Compare>
+  static Use *mergeUseLists(Use *L, Use *R, Compare Cmp) {
+    Use *Merged;
+    Use **Next = &Merged;
+
+    while (true) {
+      if (!L) {
+        *Next = R;
+        break;
+      }
+      if (!R) {
+        *Next = L;
+        break;
+      }
+      if (Cmp(*R, *L)) {
+        *Next = R;
+        Next = &R->Next;
+        R = R->Next;
+      } else {
+        *Next = L;
+        Next = &L->Next;
+        L = L->Next;
+      }
+    }
+
+    return Merged;
+  }
+
+protected:
+  unsigned short getSubclassDataFromValue() const { return SubclassData; }
+  void setValueSubclassData(unsigned short D) { SubclassData = D; }
+};
+
+struct ValueDeleter { void operator()(Value *V) { V->deleteValue(); } };
+
+/// Use this instead of std::unique_ptr<Value> or std::unique_ptr<Instruction>.
+/// Those don't work because Value and Instruction's destructors are protected,
+/// aren't virtual, and won't destroy the complete object.
+using unique_value = std::unique_ptr<Value, ValueDeleter>;
+
+inline raw_ostream &operator<<(raw_ostream &OS, const Value &V) {
+  V.print(OS);
+  return OS;
+}
+
+void Use::set(Value *V) {
+  if (Val) removeFromList();
+  Val = V;
+  if (V) V->addUse(*this);
+}
+
+Value *Use::operator=(Value *RHS) {
+  set(RHS);
+  return RHS;
+}
+
+const Use &Use::operator=(const Use &RHS) {
+  set(RHS.Val);
+  return *this;
+}
+
+template <class Compare> void Value::sortUseList(Compare Cmp) {
+  if (!UseList || !UseList->Next)
+    // No need to sort 0 or 1 uses.
+    return;
+
+  // Note: this function completely ignores Prev pointers until the end when
+  // they're fixed en masse.
+
+  // Create a binomial vector of sorted lists, visiting uses one at a time and
+  // merging lists as necessary.
+  const unsigned MaxSlots = 32;
+  Use *Slots[MaxSlots];
+
+  // Collect the first use, turning it into a single-item list.
+  Use *Next = UseList->Next;
+  UseList->Next = nullptr;
+  unsigned NumSlots = 1;
+  Slots[0] = UseList;
+
+  // Collect all but the last use.
+  while (Next->Next) {
+    Use *Current = Next;
+    Next = Current->Next;
+
+    // Turn Current into a single-item list.
+    Current->Next = nullptr;
+
+    // Save Current in the first available slot, merging on collisions.
+    unsigned I;
+    for (I = 0; I < NumSlots; ++I) {
+      if (!Slots[I])
+        break;
+
+      // Merge two lists, doubling the size of Current and emptying slot I.
+      //
+      // Since the uses in Slots[I] originally preceded those in Current, send
+      // Slots[I] in as the left parameter to maintain a stable sort.
+      Current = mergeUseLists(Slots[I], Current, Cmp);
+      Slots[I] = nullptr;
+    }
+    // Check if this is a new slot.
+    if (I == NumSlots) {
+      ++NumSlots;
+      assert(NumSlots <= MaxSlots && "Use list bigger than 2^32");
+    }
+
+    // Found an open slot.
+    Slots[I] = Current;
+  }
+
+  // Merge all the lists together.
+  assert(Next && "Expected one more Use");
+  assert(!Next->Next && "Expected only one Use");
+  UseList = Next;
+  for (unsigned I = 0; I < NumSlots; ++I)
+    if (Slots[I])
+      // Since the uses in Slots[I] originally preceded those in UseList, send
+      // Slots[I] in as the left parameter to maintain a stable sort.
+      UseList = mergeUseLists(Slots[I], UseList, Cmp);
+
+  // Fix the Prev pointers.
+  for (Use *I = UseList, **Prev = &UseList; I; I = I->Next) {
+    I->setPrev(Prev);
+    Prev = &I->Next;
+  }
+}
+
+// isa - Provide some specializations of isa so that we don't have to include
+// the subtype header files to test to see if the value is a subclass...
+//
+template <> struct isa_impl<Constant, Value> {
+  static inline bool doit(const Value &Val) {
+    static_assert(Value::ConstantFirstVal == 0, "Val.getValueID() >= Value::ConstantFirstVal");
+    return Val.getValueID() <= Value::ConstantLastVal;
+  }
+};
+
+template <> struct isa_impl<ConstantData, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() >= Value::ConstantDataFirstVal &&
+           Val.getValueID() <= Value::ConstantDataLastVal;
+  }
+};
+
+template <> struct isa_impl<ConstantAggregate, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() >= Value::ConstantAggregateFirstVal &&
+           Val.getValueID() <= Value::ConstantAggregateLastVal;
+  }
+};
+
+template <> struct isa_impl<Argument, Value> {
+  static inline bool doit (const Value &Val) {
+    return Val.getValueID() == Value::ArgumentVal;
+  }
+};
+
+template <> struct isa_impl<InlineAsm, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::InlineAsmVal;
+  }
+};
+
+template <> struct isa_impl<Instruction, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() >= Value::InstructionVal;
+  }
+};
+
+template <> struct isa_impl<BasicBlock, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::BasicBlockVal;
+  }
+};
+
+template <> struct isa_impl<Function, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::FunctionVal;
+  }
+};
+
+template <> struct isa_impl<GlobalVariable, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::GlobalVariableVal;
+  }
+};
+
+template <> struct isa_impl<GlobalAlias, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::GlobalAliasVal;
+  }
+};
+
+template <> struct isa_impl<GlobalIFunc, Value> {
+  static inline bool doit(const Value &Val) {
+    return Val.getValueID() == Value::GlobalIFuncVal;
+  }
+};
+
+template <> struct isa_impl<GlobalIndirectSymbol, Value> {
+  static inline bool doit(const Value &Val) {
+    return isa<GlobalAlias>(Val) || isa<GlobalIFunc>(Val);
+  }
+};
+
+template <> struct isa_impl<GlobalValue, Value> {
+  static inline bool doit(const Value &Val) {
+    return isa<GlobalObject>(Val) || isa<GlobalIndirectSymbol>(Val);
+  }
+};
+
+template <> struct isa_impl<GlobalObject, Value> {
+  static inline bool doit(const Value &Val) {
+    return isa<GlobalVariable>(Val) || isa<Function>(Val);
+  }
+};
+
+// Create wrappers for C Binding types (see CBindingWrapping.h).
+DEFINE_ISA_CONVERSION_FUNCTIONS(Value, LLVMValueRef)
+
+// Specialized opaque value conversions.
+inline Value **unwrap(LLVMValueRef *Vals) {
+  return reinterpret_cast<Value**>(Vals);
+}
+
+template<typename T>
+inline T **unwrap(LLVMValueRef *Vals, unsigned Length) {
+#ifndef NDEBUG
+  for (LLVMValueRef *I = Vals, *E = Vals + Length; I != E; ++I)
+    unwrap<T>(*I); // For side effect of calling assert on invalid usage.
+#endif
+  (void)Length;
+  return reinterpret_cast<T**>(Vals);
+}
+
+inline LLVMValueRef *wrap(const Value **Vals) {
+  return reinterpret_cast<LLVMValueRef*>(const_cast<Value**>(Vals));
+}
+
+} // end namespace llvm
+
+#endif // LLVM_IR_VALUE_H