Import prebuilt clang toolchain for linux.
diff --git a/linux-x64/clang/include/llvm/ADT/STLExtras.h b/linux-x64/clang/include/llvm/ADT/STLExtras.h
new file mode 100644
index 0000000..051b900
--- /dev/null
+++ b/linux-x64/clang/include/llvm/ADT/STLExtras.h
@@ -0,0 +1,1181 @@
+//===- llvm/ADT/STLExtras.h - Useful STL related functions ------*- 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 some templates that are useful if you are working with the
+// STL at all.
+//
+// No library is required when using these functions.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_ADT_STLEXTRAS_H
+#define LLVM_ADT_STLEXTRAS_H
+
+#include "llvm/ADT/Optional.h"
+#include "llvm/ADT/SmallVector.h"
+#include "llvm/ADT/iterator.h"
+#include "llvm/ADT/iterator_range.h"
+#include "llvm/Support/ErrorHandling.h"
+#include <algorithm>
+#include <cassert>
+#include <cstddef>
+#include <cstdint>
+#include <cstdlib>
+#include <functional>
+#include <initializer_list>
+#include <iterator>
+#include <limits>
+#include <memory>
+#include <tuple>
+#include <type_traits>
+#include <utility>
+
+#ifdef EXPENSIVE_CHECKS
+#include <random> // for std::mt19937
+#endif
+
+namespace llvm {
+
+// Only used by compiler if both template types are the same.  Useful when
+// using SFINAE to test for the existence of member functions.
+template <typename T, T> struct SameType;
+
+namespace detail {
+
+template <typename RangeT>
+using IterOfRange = decltype(std::begin(std::declval<RangeT &>()));
+
+template <typename RangeT>
+using ValueOfRange = typename std::remove_reference<decltype(
+    *std::begin(std::declval<RangeT &>()))>::type;
+
+} // end namespace detail
+
+//===----------------------------------------------------------------------===//
+//     Extra additions to <functional>
+//===----------------------------------------------------------------------===//
+
+template <class Ty> struct identity {
+  using argument_type = Ty;
+
+  Ty &operator()(Ty &self) const {
+    return self;
+  }
+  const Ty &operator()(const Ty &self) const {
+    return self;
+  }
+};
+
+template <class Ty> struct less_ptr {
+  bool operator()(const Ty* left, const Ty* right) const {
+    return *left < *right;
+  }
+};
+
+template <class Ty> struct greater_ptr {
+  bool operator()(const Ty* left, const Ty* right) const {
+    return *right < *left;
+  }
+};
+
+/// An efficient, type-erasing, non-owning reference to a callable. This is
+/// intended for use as the type of a function parameter that is not used
+/// after the function in question returns.
+///
+/// This class does not own the callable, so it is not in general safe to store
+/// a function_ref.
+template<typename Fn> class function_ref;
+
+template<typename Ret, typename ...Params>
+class function_ref<Ret(Params...)> {
+  Ret (*callback)(intptr_t callable, Params ...params) = nullptr;
+  intptr_t callable;
+
+  template<typename Callable>
+  static Ret callback_fn(intptr_t callable, Params ...params) {
+    return (*reinterpret_cast<Callable*>(callable))(
+        std::forward<Params>(params)...);
+  }
+
+public:
+  function_ref() = default;
+  function_ref(std::nullptr_t) {}
+
+  template <typename Callable>
+  function_ref(Callable &&callable,
+               typename std::enable_if<
+                   !std::is_same<typename std::remove_reference<Callable>::type,
+                                 function_ref>::value>::type * = nullptr)
+      : callback(callback_fn<typename std::remove_reference<Callable>::type>),
+        callable(reinterpret_cast<intptr_t>(&callable)) {}
+
+  Ret operator()(Params ...params) const {
+    return callback(callable, std::forward<Params>(params)...);
+  }
+
+  operator bool() const { return callback; }
+};
+
+// deleter - Very very very simple method that is used to invoke operator
+// delete on something.  It is used like this:
+//
+//   for_each(V.begin(), B.end(), deleter<Interval>);
+template <class T>
+inline void deleter(T *Ptr) {
+  delete Ptr;
+}
+
+//===----------------------------------------------------------------------===//
+//     Extra additions to <iterator>
+//===----------------------------------------------------------------------===//
+
+namespace adl_detail {
+
+using std::begin;
+
+template <typename ContainerTy>
+auto adl_begin(ContainerTy &&container)
+    -> decltype(begin(std::forward<ContainerTy>(container))) {
+  return begin(std::forward<ContainerTy>(container));
+}
+
+using std::end;
+
+template <typename ContainerTy>
+auto adl_end(ContainerTy &&container)
+    -> decltype(end(std::forward<ContainerTy>(container))) {
+  return end(std::forward<ContainerTy>(container));
+}
+
+using std::swap;
+
+template <typename T>
+void adl_swap(T &&lhs, T &&rhs) noexcept(noexcept(swap(std::declval<T>(),
+                                                       std::declval<T>()))) {
+  swap(std::forward<T>(lhs), std::forward<T>(rhs));
+}
+
+} // end namespace adl_detail
+
+template <typename ContainerTy>
+auto adl_begin(ContainerTy &&container)
+    -> decltype(adl_detail::adl_begin(std::forward<ContainerTy>(container))) {
+  return adl_detail::adl_begin(std::forward<ContainerTy>(container));
+}
+
+template <typename ContainerTy>
+auto adl_end(ContainerTy &&container)
+    -> decltype(adl_detail::adl_end(std::forward<ContainerTy>(container))) {
+  return adl_detail::adl_end(std::forward<ContainerTy>(container));
+}
+
+template <typename T>
+void adl_swap(T &&lhs, T &&rhs) noexcept(
+    noexcept(adl_detail::adl_swap(std::declval<T>(), std::declval<T>()))) {
+  adl_detail::adl_swap(std::forward<T>(lhs), std::forward<T>(rhs));
+}
+
+// mapped_iterator - This is a simple iterator adapter that causes a function to
+// be applied whenever operator* is invoked on the iterator.
+
+template <typename ItTy, typename FuncTy,
+          typename FuncReturnTy =
+            decltype(std::declval<FuncTy>()(*std::declval<ItTy>()))>
+class mapped_iterator
+    : public iterator_adaptor_base<
+             mapped_iterator<ItTy, FuncTy>, ItTy,
+             typename std::iterator_traits<ItTy>::iterator_category,
+             typename std::remove_reference<FuncReturnTy>::type> {
+public:
+  mapped_iterator(ItTy U, FuncTy F)
+    : mapped_iterator::iterator_adaptor_base(std::move(U)), F(std::move(F)) {}
+
+  ItTy getCurrent() { return this->I; }
+
+  FuncReturnTy operator*() { return F(*this->I); }
+
+private:
+  FuncTy F;
+};
+
+// map_iterator - Provide a convenient way to create mapped_iterators, just like
+// make_pair is useful for creating pairs...
+template <class ItTy, class FuncTy>
+inline mapped_iterator<ItTy, FuncTy> map_iterator(ItTy I, FuncTy F) {
+  return mapped_iterator<ItTy, FuncTy>(std::move(I), std::move(F));
+}
+
+/// Helper to determine if type T has a member called rbegin().
+template <typename Ty> class has_rbegin_impl {
+  using yes = char[1];
+  using no = char[2];
+
+  template <typename Inner>
+  static yes& test(Inner *I, decltype(I->rbegin()) * = nullptr);
+
+  template <typename>
+  static no& test(...);
+
+public:
+  static const bool value = sizeof(test<Ty>(nullptr)) == sizeof(yes);
+};
+
+/// Metafunction to determine if T& or T has a member called rbegin().
+template <typename Ty>
+struct has_rbegin : has_rbegin_impl<typename std::remove_reference<Ty>::type> {
+};
+
+// Returns an iterator_range over the given container which iterates in reverse.
+// Note that the container must have rbegin()/rend() methods for this to work.
+template <typename ContainerTy>
+auto reverse(ContainerTy &&C,
+             typename std::enable_if<has_rbegin<ContainerTy>::value>::type * =
+                 nullptr) -> decltype(make_range(C.rbegin(), C.rend())) {
+  return make_range(C.rbegin(), C.rend());
+}
+
+// Returns a std::reverse_iterator wrapped around the given iterator.
+template <typename IteratorTy>
+std::reverse_iterator<IteratorTy> make_reverse_iterator(IteratorTy It) {
+  return std::reverse_iterator<IteratorTy>(It);
+}
+
+// Returns an iterator_range over the given container which iterates in reverse.
+// Note that the container must have begin()/end() methods which return
+// bidirectional iterators for this to work.
+template <typename ContainerTy>
+auto reverse(
+    ContainerTy &&C,
+    typename std::enable_if<!has_rbegin<ContainerTy>::value>::type * = nullptr)
+    -> decltype(make_range(llvm::make_reverse_iterator(std::end(C)),
+                           llvm::make_reverse_iterator(std::begin(C)))) {
+  return make_range(llvm::make_reverse_iterator(std::end(C)),
+                    llvm::make_reverse_iterator(std::begin(C)));
+}
+
+/// An iterator adaptor that filters the elements of given inner iterators.
+///
+/// The predicate parameter should be a callable object that accepts the wrapped
+/// iterator's reference type and returns a bool. When incrementing or
+/// decrementing the iterator, it will call the predicate on each element and
+/// skip any where it returns false.
+///
+/// \code
+///   int A[] = { 1, 2, 3, 4 };
+///   auto R = make_filter_range(A, [](int N) { return N % 2 == 1; });
+///   // R contains { 1, 3 }.
+/// \endcode
+template <typename WrappedIteratorT, typename PredicateT>
+class filter_iterator
+    : public iterator_adaptor_base<
+          filter_iterator<WrappedIteratorT, PredicateT>, WrappedIteratorT,
+          typename std::common_type<
+              std::forward_iterator_tag,
+              typename std::iterator_traits<
+                  WrappedIteratorT>::iterator_category>::type> {
+  using BaseT = iterator_adaptor_base<
+      filter_iterator<WrappedIteratorT, PredicateT>, WrappedIteratorT,
+      typename std::common_type<
+          std::forward_iterator_tag,
+          typename std::iterator_traits<WrappedIteratorT>::iterator_category>::
+          type>;
+
+  struct PayloadType {
+    WrappedIteratorT End;
+    PredicateT Pred;
+  };
+
+  Optional<PayloadType> Payload;
+
+  void findNextValid() {
+    assert(Payload && "Payload should be engaged when findNextValid is called");
+    while (this->I != Payload->End && !Payload->Pred(*this->I))
+      BaseT::operator++();
+  }
+
+  // Construct the begin iterator. The begin iterator requires to know where end
+  // is, so that it can properly stop when it hits end.
+  filter_iterator(WrappedIteratorT Begin, WrappedIteratorT End, PredicateT Pred)
+      : BaseT(std::move(Begin)),
+        Payload(PayloadType{std::move(End), std::move(Pred)}) {
+    findNextValid();
+  }
+
+  // Construct the end iterator. It's not incrementable, so Payload doesn't
+  // have to be engaged.
+  filter_iterator(WrappedIteratorT End) : BaseT(End) {}
+
+public:
+  using BaseT::operator++;
+
+  filter_iterator &operator++() {
+    BaseT::operator++();
+    findNextValid();
+    return *this;
+  }
+
+  template <typename RT, typename PT>
+  friend iterator_range<filter_iterator<detail::IterOfRange<RT>, PT>>
+  make_filter_range(RT &&, PT);
+};
+
+/// Convenience function that takes a range of elements and a predicate,
+/// and return a new filter_iterator range.
+///
+/// FIXME: Currently if RangeT && is a rvalue reference to a temporary, the
+/// lifetime of that temporary is not kept by the returned range object, and the
+/// temporary is going to be dropped on the floor after the make_iterator_range
+/// full expression that contains this function call.
+template <typename RangeT, typename PredicateT>
+iterator_range<filter_iterator<detail::IterOfRange<RangeT>, PredicateT>>
+make_filter_range(RangeT &&Range, PredicateT Pred) {
+  using FilterIteratorT =
+      filter_iterator<detail::IterOfRange<RangeT>, PredicateT>;
+  return make_range(FilterIteratorT(std::begin(std::forward<RangeT>(Range)),
+                                    std::end(std::forward<RangeT>(Range)),
+                                    std::move(Pred)),
+                    FilterIteratorT(std::end(std::forward<RangeT>(Range))));
+}
+
+// forward declarations required by zip_shortest/zip_first
+template <typename R, typename UnaryPredicate>
+bool all_of(R &&range, UnaryPredicate P);
+
+template <size_t... I> struct index_sequence;
+
+template <class... Ts> struct index_sequence_for;
+
+namespace detail {
+
+using std::declval;
+
+// We have to alias this since inlining the actual type at the usage site
+// in the parameter list of iterator_facade_base<> below ICEs MSVC 2017.
+template<typename... Iters> struct ZipTupleType {
+  using type = std::tuple<decltype(*declval<Iters>())...>;
+};
+
+template <typename ZipType, typename... Iters>
+using zip_traits = iterator_facade_base<
+    ZipType, typename std::common_type<std::bidirectional_iterator_tag,
+                                       typename std::iterator_traits<
+                                           Iters>::iterator_category...>::type,
+    // ^ TODO: Implement random access methods.
+    typename ZipTupleType<Iters...>::type,
+    typename std::iterator_traits<typename std::tuple_element<
+        0, std::tuple<Iters...>>::type>::difference_type,
+    // ^ FIXME: This follows boost::make_zip_iterator's assumption that all
+    // inner iterators have the same difference_type. It would fail if, for
+    // instance, the second field's difference_type were non-numeric while the
+    // first is.
+    typename ZipTupleType<Iters...>::type *,
+    typename ZipTupleType<Iters...>::type>;
+
+template <typename ZipType, typename... Iters>
+struct zip_common : public zip_traits<ZipType, Iters...> {
+  using Base = zip_traits<ZipType, Iters...>;
+  using value_type = typename Base::value_type;
+
+  std::tuple<Iters...> iterators;
+
+protected:
+  template <size_t... Ns> value_type deref(index_sequence<Ns...>) const {
+    return value_type(*std::get<Ns>(iterators)...);
+  }
+
+  template <size_t... Ns>
+  decltype(iterators) tup_inc(index_sequence<Ns...>) const {
+    return std::tuple<Iters...>(std::next(std::get<Ns>(iterators))...);
+  }
+
+  template <size_t... Ns>
+  decltype(iterators) tup_dec(index_sequence<Ns...>) const {
+    return std::tuple<Iters...>(std::prev(std::get<Ns>(iterators))...);
+  }
+
+public:
+  zip_common(Iters &&... ts) : iterators(std::forward<Iters>(ts)...) {}
+
+  value_type operator*() { return deref(index_sequence_for<Iters...>{}); }
+
+  const value_type operator*() const {
+    return deref(index_sequence_for<Iters...>{});
+  }
+
+  ZipType &operator++() {
+    iterators = tup_inc(index_sequence_for<Iters...>{});
+    return *reinterpret_cast<ZipType *>(this);
+  }
+
+  ZipType &operator--() {
+    static_assert(Base::IsBidirectional,
+                  "All inner iterators must be at least bidirectional.");
+    iterators = tup_dec(index_sequence_for<Iters...>{});
+    return *reinterpret_cast<ZipType *>(this);
+  }
+};
+
+template <typename... Iters>
+struct zip_first : public zip_common<zip_first<Iters...>, Iters...> {
+  using Base = zip_common<zip_first<Iters...>, Iters...>;
+
+  bool operator==(const zip_first<Iters...> &other) const {
+    return std::get<0>(this->iterators) == std::get<0>(other.iterators);
+  }
+
+  zip_first(Iters &&... ts) : Base(std::forward<Iters>(ts)...) {}
+};
+
+template <typename... Iters>
+class zip_shortest : public zip_common<zip_shortest<Iters...>, Iters...> {
+  template <size_t... Ns>
+  bool test(const zip_shortest<Iters...> &other, index_sequence<Ns...>) const {
+    return all_of(std::initializer_list<bool>{std::get<Ns>(this->iterators) !=
+                                              std::get<Ns>(other.iterators)...},
+                  identity<bool>{});
+  }
+
+public:
+  using Base = zip_common<zip_shortest<Iters...>, Iters...>;
+
+  zip_shortest(Iters &&... ts) : Base(std::forward<Iters>(ts)...) {}
+
+  bool operator==(const zip_shortest<Iters...> &other) const {
+    return !test(other, index_sequence_for<Iters...>{});
+  }
+};
+
+template <template <typename...> class ItType, typename... Args> class zippy {
+public:
+  using iterator = ItType<decltype(std::begin(std::declval<Args>()))...>;
+  using iterator_category = typename iterator::iterator_category;
+  using value_type = typename iterator::value_type;
+  using difference_type = typename iterator::difference_type;
+  using pointer = typename iterator::pointer;
+  using reference = typename iterator::reference;
+
+private:
+  std::tuple<Args...> ts;
+
+  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) const {
+    return iterator(std::begin(std::get<Ns>(ts))...);
+  }
+  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) const {
+    return iterator(std::end(std::get<Ns>(ts))...);
+  }
+
+public:
+  zippy(Args &&... ts_) : ts(std::forward<Args>(ts_)...) {}
+
+  iterator begin() const { return begin_impl(index_sequence_for<Args...>{}); }
+  iterator end() const { return end_impl(index_sequence_for<Args...>{}); }
+};
+
+} // end namespace detail
+
+/// zip iterator for two or more iteratable types.
+template <typename T, typename U, typename... Args>
+detail::zippy<detail::zip_shortest, T, U, Args...> zip(T &&t, U &&u,
+                                                       Args &&... args) {
+  return detail::zippy<detail::zip_shortest, T, U, Args...>(
+      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
+}
+
+/// zip iterator that, for the sake of efficiency, assumes the first iteratee to
+/// be the shortest.
+template <typename T, typename U, typename... Args>
+detail::zippy<detail::zip_first, T, U, Args...> zip_first(T &&t, U &&u,
+                                                          Args &&... args) {
+  return detail::zippy<detail::zip_first, T, U, Args...>(
+      std::forward<T>(t), std::forward<U>(u), std::forward<Args>(args)...);
+}
+
+/// Iterator wrapper that concatenates sequences together.
+///
+/// This can concatenate different iterators, even with different types, into
+/// a single iterator provided the value types of all the concatenated
+/// iterators expose `reference` and `pointer` types that can be converted to
+/// `ValueT &` and `ValueT *` respectively. It doesn't support more
+/// interesting/customized pointer or reference types.
+///
+/// Currently this only supports forward or higher iterator categories as
+/// inputs and always exposes a forward iterator interface.
+template <typename ValueT, typename... IterTs>
+class concat_iterator
+    : public iterator_facade_base<concat_iterator<ValueT, IterTs...>,
+                                  std::forward_iterator_tag, ValueT> {
+  using BaseT = typename concat_iterator::iterator_facade_base;
+
+  /// We store both the current and end iterators for each concatenated
+  /// sequence in a tuple of pairs.
+  ///
+  /// Note that something like iterator_range seems nice at first here, but the
+  /// range properties are of little benefit and end up getting in the way
+  /// because we need to do mutation on the current iterators.
+  std::tuple<std::pair<IterTs, IterTs>...> IterPairs;
+
+  /// Attempts to increment a specific iterator.
+  ///
+  /// Returns true if it was able to increment the iterator. Returns false if
+  /// the iterator is already at the end iterator.
+  template <size_t Index> bool incrementHelper() {
+    auto &IterPair = std::get<Index>(IterPairs);
+    if (IterPair.first == IterPair.second)
+      return false;
+
+    ++IterPair.first;
+    return true;
+  }
+
+  /// Increments the first non-end iterator.
+  ///
+  /// It is an error to call this with all iterators at the end.
+  template <size_t... Ns> void increment(index_sequence<Ns...>) {
+    // Build a sequence of functions to increment each iterator if possible.
+    bool (concat_iterator::*IncrementHelperFns[])() = {
+        &concat_iterator::incrementHelper<Ns>...};
+
+    // Loop over them, and stop as soon as we succeed at incrementing one.
+    for (auto &IncrementHelperFn : IncrementHelperFns)
+      if ((this->*IncrementHelperFn)())
+        return;
+
+    llvm_unreachable("Attempted to increment an end concat iterator!");
+  }
+
+  /// Returns null if the specified iterator is at the end. Otherwise,
+  /// dereferences the iterator and returns the address of the resulting
+  /// reference.
+  template <size_t Index> ValueT *getHelper() const {
+    auto &IterPair = std::get<Index>(IterPairs);
+    if (IterPair.first == IterPair.second)
+      return nullptr;
+
+    return &*IterPair.first;
+  }
+
+  /// Finds the first non-end iterator, dereferences, and returns the resulting
+  /// reference.
+  ///
+  /// It is an error to call this with all iterators at the end.
+  template <size_t... Ns> ValueT &get(index_sequence<Ns...>) const {
+    // Build a sequence of functions to get from iterator if possible.
+    ValueT *(concat_iterator::*GetHelperFns[])() const = {
+        &concat_iterator::getHelper<Ns>...};
+
+    // Loop over them, and return the first result we find.
+    for (auto &GetHelperFn : GetHelperFns)
+      if (ValueT *P = (this->*GetHelperFn)())
+        return *P;
+
+    llvm_unreachable("Attempted to get a pointer from an end concat iterator!");
+  }
+
+public:
+  /// Constructs an iterator from a squence of ranges.
+  ///
+  /// We need the full range to know how to switch between each of the
+  /// iterators.
+  template <typename... RangeTs>
+  explicit concat_iterator(RangeTs &&... Ranges)
+      : IterPairs({std::begin(Ranges), std::end(Ranges)}...) {}
+
+  using BaseT::operator++;
+
+  concat_iterator &operator++() {
+    increment(index_sequence_for<IterTs...>());
+    return *this;
+  }
+
+  ValueT &operator*() const { return get(index_sequence_for<IterTs...>()); }
+
+  bool operator==(const concat_iterator &RHS) const {
+    return IterPairs == RHS.IterPairs;
+  }
+};
+
+namespace detail {
+
+/// Helper to store a sequence of ranges being concatenated and access them.
+///
+/// This is designed to facilitate providing actual storage when temporaries
+/// are passed into the constructor such that we can use it as part of range
+/// based for loops.
+template <typename ValueT, typename... RangeTs> class concat_range {
+public:
+  using iterator =
+      concat_iterator<ValueT,
+                      decltype(std::begin(std::declval<RangeTs &>()))...>;
+
+private:
+  std::tuple<RangeTs...> Ranges;
+
+  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) {
+    return iterator(std::get<Ns>(Ranges)...);
+  }
+  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) {
+    return iterator(make_range(std::end(std::get<Ns>(Ranges)),
+                               std::end(std::get<Ns>(Ranges)))...);
+  }
+
+public:
+  concat_range(RangeTs &&... Ranges)
+      : Ranges(std::forward<RangeTs>(Ranges)...) {}
+
+  iterator begin() { return begin_impl(index_sequence_for<RangeTs...>{}); }
+  iterator end() { return end_impl(index_sequence_for<RangeTs...>{}); }
+};
+
+} // end namespace detail
+
+/// Concatenated range across two or more ranges.
+///
+/// The desired value type must be explicitly specified.
+template <typename ValueT, typename... RangeTs>
+detail::concat_range<ValueT, RangeTs...> concat(RangeTs &&... Ranges) {
+  static_assert(sizeof...(RangeTs) > 1,
+                "Need more than one range to concatenate!");
+  return detail::concat_range<ValueT, RangeTs...>(
+      std::forward<RangeTs>(Ranges)...);
+}
+
+//===----------------------------------------------------------------------===//
+//     Extra additions to <utility>
+//===----------------------------------------------------------------------===//
+
+/// \brief Function object to check whether the first component of a std::pair
+/// compares less than the first component of another std::pair.
+struct less_first {
+  template <typename T> bool operator()(const T &lhs, const T &rhs) const {
+    return lhs.first < rhs.first;
+  }
+};
+
+/// \brief Function object to check whether the second component of a std::pair
+/// compares less than the second component of another std::pair.
+struct less_second {
+  template <typename T> bool operator()(const T &lhs, const T &rhs) const {
+    return lhs.second < rhs.second;
+  }
+};
+
+// A subset of N3658. More stuff can be added as-needed.
+
+/// \brief Represents a compile-time sequence of integers.
+template <class T, T... I> struct integer_sequence {
+  using value_type = T;
+
+  static constexpr size_t size() { return sizeof...(I); }
+};
+
+/// \brief Alias for the common case of a sequence of size_ts.
+template <size_t... I>
+struct index_sequence : integer_sequence<std::size_t, I...> {};
+
+template <std::size_t N, std::size_t... I>
+struct build_index_impl : build_index_impl<N - 1, N - 1, I...> {};
+template <std::size_t... I>
+struct build_index_impl<0, I...> : index_sequence<I...> {};
+
+/// \brief Creates a compile-time integer sequence for a parameter pack.
+template <class... Ts>
+struct index_sequence_for : build_index_impl<sizeof...(Ts)> {};
+
+/// Utility type to build an inheritance chain that makes it easy to rank
+/// overload candidates.
+template <int N> struct rank : rank<N - 1> {};
+template <> struct rank<0> {};
+
+/// \brief traits class for checking whether type T is one of any of the given
+/// types in the variadic list.
+template <typename T, typename... Ts> struct is_one_of {
+  static const bool value = false;
+};
+
+template <typename T, typename U, typename... Ts>
+struct is_one_of<T, U, Ts...> {
+  static const bool value =
+      std::is_same<T, U>::value || is_one_of<T, Ts...>::value;
+};
+
+/// \brief traits class for checking whether type T is a base class for all
+///  the given types in the variadic list.
+template <typename T, typename... Ts> struct are_base_of {
+  static const bool value = true;
+};
+
+template <typename T, typename U, typename... Ts>
+struct are_base_of<T, U, Ts...> {
+  static const bool value =
+      std::is_base_of<T, U>::value && are_base_of<T, Ts...>::value;
+};
+
+//===----------------------------------------------------------------------===//
+//     Extra additions for arrays
+//===----------------------------------------------------------------------===//
+
+/// Find the length of an array.
+template <class T, std::size_t N>
+constexpr inline size_t array_lengthof(T (&)[N]) {
+  return N;
+}
+
+/// Adapt std::less<T> for array_pod_sort.
+template<typename T>
+inline int array_pod_sort_comparator(const void *P1, const void *P2) {
+  if (std::less<T>()(*reinterpret_cast<const T*>(P1),
+                     *reinterpret_cast<const T*>(P2)))
+    return -1;
+  if (std::less<T>()(*reinterpret_cast<const T*>(P2),
+                     *reinterpret_cast<const T*>(P1)))
+    return 1;
+  return 0;
+}
+
+/// get_array_pod_sort_comparator - This is an internal helper function used to
+/// get type deduction of T right.
+template<typename T>
+inline int (*get_array_pod_sort_comparator(const T &))
+             (const void*, const void*) {
+  return array_pod_sort_comparator<T>;
+}
+
+/// array_pod_sort - This sorts an array with the specified start and end
+/// extent.  This is just like std::sort, except that it calls qsort instead of
+/// using an inlined template.  qsort is slightly slower than std::sort, but
+/// most sorts are not performance critical in LLVM and std::sort has to be
+/// template instantiated for each type, leading to significant measured code
+/// bloat.  This function should generally be used instead of std::sort where
+/// possible.
+///
+/// This function assumes that you have simple POD-like types that can be
+/// compared with std::less and can be moved with memcpy.  If this isn't true,
+/// you should use std::sort.
+///
+/// NOTE: If qsort_r were portable, we could allow a custom comparator and
+/// default to std::less.
+template<class IteratorTy>
+inline void array_pod_sort(IteratorTy Start, IteratorTy End) {
+  // Don't inefficiently call qsort with one element or trigger undefined
+  // behavior with an empty sequence.
+  auto NElts = End - Start;
+  if (NElts <= 1) return;
+#ifdef EXPENSIVE_CHECKS
+  std::mt19937 Generator(std::random_device{}());
+  std::shuffle(Start, End, Generator);
+#endif
+  qsort(&*Start, NElts, sizeof(*Start), get_array_pod_sort_comparator(*Start));
+}
+
+template <class IteratorTy>
+inline void array_pod_sort(
+    IteratorTy Start, IteratorTy End,
+    int (*Compare)(
+        const typename std::iterator_traits<IteratorTy>::value_type *,
+        const typename std::iterator_traits<IteratorTy>::value_type *)) {
+  // Don't inefficiently call qsort with one element or trigger undefined
+  // behavior with an empty sequence.
+  auto NElts = End - Start;
+  if (NElts <= 1) return;
+#ifdef EXPENSIVE_CHECKS
+  std::mt19937 Generator(std::random_device{}());
+  std::shuffle(Start, End, Generator);
+#endif
+  qsort(&*Start, NElts, sizeof(*Start),
+        reinterpret_cast<int (*)(const void *, const void *)>(Compare));
+}
+
+// Provide wrappers to std::sort which shuffle the elements before sorting
+// to help uncover non-deterministic behavior (PR35135).
+template <typename IteratorTy>
+inline void sort(IteratorTy Start, IteratorTy End) {
+#ifdef EXPENSIVE_CHECKS
+  std::mt19937 Generator(std::random_device{}());
+  std::shuffle(Start, End, Generator);
+#endif
+  std::sort(Start, End);
+}
+
+template <typename IteratorTy, typename Compare>
+inline void sort(IteratorTy Start, IteratorTy End, Compare Comp) {
+#ifdef EXPENSIVE_CHECKS
+  std::mt19937 Generator(std::random_device{}());
+  std::shuffle(Start, End, Generator);
+#endif
+  std::sort(Start, End, Comp);
+}
+
+//===----------------------------------------------------------------------===//
+//     Extra additions to <algorithm>
+//===----------------------------------------------------------------------===//
+
+/// For a container of pointers, deletes the pointers and then clears the
+/// container.
+template<typename Container>
+void DeleteContainerPointers(Container &C) {
+  for (auto V : C)
+    delete V;
+  C.clear();
+}
+
+/// In a container of pairs (usually a map) whose second element is a pointer,
+/// deletes the second elements and then clears the container.
+template<typename Container>
+void DeleteContainerSeconds(Container &C) {
+  for (auto &V : C)
+    delete V.second;
+  C.clear();
+}
+
+/// Provide wrappers to std::for_each which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+UnaryPredicate for_each(R &&Range, UnaryPredicate P) {
+  return std::for_each(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::all_of which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+bool all_of(R &&Range, UnaryPredicate P) {
+  return std::all_of(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::any_of which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+bool any_of(R &&Range, UnaryPredicate P) {
+  return std::any_of(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::none_of which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+bool none_of(R &&Range, UnaryPredicate P) {
+  return std::none_of(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::find which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, typename T>
+auto find(R &&Range, const T &Val) -> decltype(adl_begin(Range)) {
+  return std::find(adl_begin(Range), adl_end(Range), Val);
+}
+
+/// Provide wrappers to std::find_if which take ranges instead of having to pass
+/// begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+auto find_if(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range)) {
+  return std::find_if(adl_begin(Range), adl_end(Range), P);
+}
+
+template <typename R, typename UnaryPredicate>
+auto find_if_not(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range)) {
+  return std::find_if_not(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::remove_if which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+auto remove_if(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range)) {
+  return std::remove_if(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::copy_if which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename OutputIt, typename UnaryPredicate>
+OutputIt copy_if(R &&Range, OutputIt Out, UnaryPredicate P) {
+  return std::copy_if(adl_begin(Range), adl_end(Range), Out, P);
+}
+
+template <typename R, typename OutputIt>
+OutputIt copy(R &&Range, OutputIt Out) {
+  return std::copy(adl_begin(Range), adl_end(Range), Out);
+}
+
+/// Wrapper function around std::find to detect if an element exists
+/// in a container.
+template <typename R, typename E>
+bool is_contained(R &&Range, const E &Element) {
+  return std::find(adl_begin(Range), adl_end(Range), Element) != adl_end(Range);
+}
+
+/// Wrapper function around std::count to count the number of times an element
+/// \p Element occurs in the given range \p Range.
+template <typename R, typename E>
+auto count(R &&Range, const E &Element) ->
+    typename std::iterator_traits<decltype(adl_begin(Range))>::difference_type {
+  return std::count(adl_begin(Range), adl_end(Range), Element);
+}
+
+/// Wrapper function around std::count_if to count the number of times an
+/// element satisfying a given predicate occurs in a range.
+template <typename R, typename UnaryPredicate>
+auto count_if(R &&Range, UnaryPredicate P) ->
+    typename std::iterator_traits<decltype(adl_begin(Range))>::difference_type {
+  return std::count_if(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Wrapper function around std::transform to apply a function to a range and
+/// store the result elsewhere.
+template <typename R, typename OutputIt, typename UnaryPredicate>
+OutputIt transform(R &&Range, OutputIt d_first, UnaryPredicate P) {
+  return std::transform(adl_begin(Range), adl_end(Range), d_first, P);
+}
+
+/// Provide wrappers to std::partition which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename UnaryPredicate>
+auto partition(R &&Range, UnaryPredicate P) -> decltype(adl_begin(Range)) {
+  return std::partition(adl_begin(Range), adl_end(Range), P);
+}
+
+/// Provide wrappers to std::lower_bound which take ranges instead of having to
+/// pass begin/end explicitly.
+template <typename R, typename ForwardIt>
+auto lower_bound(R &&Range, ForwardIt I) -> decltype(adl_begin(Range)) {
+  return std::lower_bound(adl_begin(Range), adl_end(Range), I);
+}
+
+/// \brief Given a range of type R, iterate the entire range and return a
+/// SmallVector with elements of the vector.  This is useful, for example,
+/// when you want to iterate a range and then sort the results.
+template <unsigned Size, typename R>
+SmallVector<typename std::remove_const<detail::ValueOfRange<R>>::type, Size>
+to_vector(R &&Range) {
+  return {adl_begin(Range), adl_end(Range)};
+}
+
+/// Provide a container algorithm similar to C++ Library Fundamentals v2's
+/// `erase_if` which is equivalent to:
+///
+///   C.erase(remove_if(C, pred), C.end());
+///
+/// This version works for any container with an erase method call accepting
+/// two iterators.
+template <typename Container, typename UnaryPredicate>
+void erase_if(Container &C, UnaryPredicate P) {
+  C.erase(remove_if(C, P), C.end());
+}
+
+//===----------------------------------------------------------------------===//
+//     Extra additions to <memory>
+//===----------------------------------------------------------------------===//
+
+// Implement make_unique according to N3656.
+
+/// \brief Constructs a `new T()` with the given args and returns a
+///        `unique_ptr<T>` which owns the object.
+///
+/// Example:
+///
+///     auto p = make_unique<int>();
+///     auto p = make_unique<std::tuple<int, int>>(0, 1);
+template <class T, class... Args>
+typename std::enable_if<!std::is_array<T>::value, std::unique_ptr<T>>::type
+make_unique(Args &&... args) {
+  return std::unique_ptr<T>(new T(std::forward<Args>(args)...));
+}
+
+/// \brief Constructs a `new T[n]` with the given args and returns a
+///        `unique_ptr<T[]>` which owns the object.
+///
+/// \param n size of the new array.
+///
+/// Example:
+///
+///     auto p = make_unique<int[]>(2); // value-initializes the array with 0's.
+template <class T>
+typename std::enable_if<std::is_array<T>::value && std::extent<T>::value == 0,
+                        std::unique_ptr<T>>::type
+make_unique(size_t n) {
+  return std::unique_ptr<T>(new typename std::remove_extent<T>::type[n]());
+}
+
+/// This function isn't used and is only here to provide better compile errors.
+template <class T, class... Args>
+typename std::enable_if<std::extent<T>::value != 0>::type
+make_unique(Args &&...) = delete;
+
+struct FreeDeleter {
+  void operator()(void* v) {
+    ::free(v);
+  }
+};
+
+template<typename First, typename Second>
+struct pair_hash {
+  size_t operator()(const std::pair<First, Second> &P) const {
+    return std::hash<First>()(P.first) * 31 + std::hash<Second>()(P.second);
+  }
+};
+
+/// A functor like C++14's std::less<void> in its absence.
+struct less {
+  template <typename A, typename B> bool operator()(A &&a, B &&b) const {
+    return std::forward<A>(a) < std::forward<B>(b);
+  }
+};
+
+/// A functor like C++14's std::equal<void> in its absence.
+struct equal {
+  template <typename A, typename B> bool operator()(A &&a, B &&b) const {
+    return std::forward<A>(a) == std::forward<B>(b);
+  }
+};
+
+/// Binary functor that adapts to any other binary functor after dereferencing
+/// operands.
+template <typename T> struct deref {
+  T func;
+
+  // Could be further improved to cope with non-derivable functors and
+  // non-binary functors (should be a variadic template member function
+  // operator()).
+  template <typename A, typename B>
+  auto operator()(A &lhs, B &rhs) const -> decltype(func(*lhs, *rhs)) {
+    assert(lhs);
+    assert(rhs);
+    return func(*lhs, *rhs);
+  }
+};
+
+namespace detail {
+
+template <typename R> class enumerator_iter;
+
+template <typename R> struct result_pair {
+  friend class enumerator_iter<R>;
+
+  result_pair() = default;
+  result_pair(std::size_t Index, IterOfRange<R> Iter)
+      : Index(Index), Iter(Iter) {}
+
+  result_pair<R> &operator=(const result_pair<R> &Other) {
+    Index = Other.Index;
+    Iter = Other.Iter;
+    return *this;
+  }
+
+  std::size_t index() const { return Index; }
+  const ValueOfRange<R> &value() const { return *Iter; }
+  ValueOfRange<R> &value() { return *Iter; }
+
+private:
+  std::size_t Index = std::numeric_limits<std::size_t>::max();
+  IterOfRange<R> Iter;
+};
+
+template <typename R>
+class enumerator_iter
+    : public iterator_facade_base<
+          enumerator_iter<R>, std::forward_iterator_tag, result_pair<R>,
+          typename std::iterator_traits<IterOfRange<R>>::difference_type,
+          typename std::iterator_traits<IterOfRange<R>>::pointer,
+          typename std::iterator_traits<IterOfRange<R>>::reference> {
+  using result_type = result_pair<R>;
+
+public:
+  explicit enumerator_iter(IterOfRange<R> EndIter)
+      : Result(std::numeric_limits<size_t>::max(), EndIter) {}
+
+  enumerator_iter(std::size_t Index, IterOfRange<R> Iter)
+      : Result(Index, Iter) {}
+
+  result_type &operator*() { return Result; }
+  const result_type &operator*() const { return Result; }
+
+  enumerator_iter<R> &operator++() {
+    assert(Result.Index != std::numeric_limits<size_t>::max());
+    ++Result.Iter;
+    ++Result.Index;
+    return *this;
+  }
+
+  bool operator==(const enumerator_iter<R> &RHS) const {
+    // Don't compare indices here, only iterators.  It's possible for an end
+    // iterator to have different indices depending on whether it was created
+    // by calling std::end() versus incrementing a valid iterator.
+    return Result.Iter == RHS.Result.Iter;
+  }
+
+  enumerator_iter<R> &operator=(const enumerator_iter<R> &Other) {
+    Result = Other.Result;
+    return *this;
+  }
+
+private:
+  result_type Result;
+};
+
+template <typename R> class enumerator {
+public:
+  explicit enumerator(R &&Range) : TheRange(std::forward<R>(Range)) {}
+
+  enumerator_iter<R> begin() {
+    return enumerator_iter<R>(0, std::begin(TheRange));
+  }
+
+  enumerator_iter<R> end() {
+    return enumerator_iter<R>(std::end(TheRange));
+  }
+
+private:
+  R TheRange;
+};
+
+} // end namespace detail
+
+/// Given an input range, returns a new range whose values are are pair (A,B)
+/// such that A is the 0-based index of the item in the sequence, and B is
+/// the value from the original sequence.  Example:
+///
+/// std::vector<char> Items = {'A', 'B', 'C', 'D'};
+/// for (auto X : enumerate(Items)) {
+///   printf("Item %d - %c\n", X.index(), X.value());
+/// }
+///
+/// Output:
+///   Item 0 - A
+///   Item 1 - B
+///   Item 2 - C
+///   Item 3 - D
+///
+template <typename R> detail::enumerator<R> enumerate(R &&TheRange) {
+  return detail::enumerator<R>(std::forward<R>(TheRange));
+}
+
+namespace detail {
+
+template <typename F, typename Tuple, std::size_t... I>
+auto apply_tuple_impl(F &&f, Tuple &&t, index_sequence<I...>)
+    -> decltype(std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...)) {
+  return std::forward<F>(f)(std::get<I>(std::forward<Tuple>(t))...);
+}
+
+} // end namespace detail
+
+/// Given an input tuple (a1, a2, ..., an), pass the arguments of the
+/// tuple variadically to f as if by calling f(a1, a2, ..., an) and
+/// return the result.
+template <typename F, typename Tuple>
+auto apply_tuple(F &&f, Tuple &&t) -> decltype(detail::apply_tuple_impl(
+    std::forward<F>(f), std::forward<Tuple>(t),
+    build_index_impl<
+        std::tuple_size<typename std::decay<Tuple>::type>::value>{})) {
+  using Indices = build_index_impl<
+      std::tuple_size<typename std::decay<Tuple>::type>::value>;
+
+  return detail::apply_tuple_impl(std::forward<F>(f), std::forward<Tuple>(t),
+                                  Indices{});
+}
+
+} // end namespace llvm
+
+#endif // LLVM_ADT_STLEXTRAS_H