From 37508d3dd94b0154861a90b1909d17b01400df99 Mon Sep 17 00:00:00 2001
From: Benjamin Kramer <benny.kra@googlemail.com>
Date: Thu, 15 Aug 2019 10:56:05 +0000
Subject: [PATCH] Replace llvm::integer_sequence and friends with the C++14
 standard version

The implementation in libc++ takes O(1) compile time, ours was O(n).

llvm-svn: 368990
---
 clang-tools-extra/clangd/Function.h           |   4 +-
 clang-tools-extra/clangd/unittests/Matchers.h |   4 +-
 .../clang/ASTMatchers/ASTMatchersInternal.h   |   4 +-
 clang/include/clang/Sema/Sema.h               |   4 +-
 .../RefactoringActionRulesInternal.h          |   8 +-
 clang/lib/CodeGen/EHScopeStack.h              |   4 +-
 llvm/include/llvm/ADT/STLExtras.h             | 107 ++++++++----------
 .../ExecutionEngine/Orc/RPCSerialization.h    |   8 +-
 .../llvm/ExecutionEngine/Orc/RPCUtils.h       |  15 +--
 llvm/include/llvm/IR/PassManager.h            |   4 +-
 llvm/include/llvm/Support/Format.h            |   5 +-
 11 files changed, 75 insertions(+), 92 deletions(-)

diff --git a/clang-tools-extra/clangd/Function.h b/clang-tools-extra/clangd/Function.h
index 6d91136bf994..91aaa48a9fff 100644
--- a/clang-tools-extra/clangd/Function.h
+++ b/clang-tools-extra/clangd/Function.h
@@ -59,14 +59,14 @@ private:
 public:
   template <class... RestArgs>
   auto operator()(RestArgs &&... Rest)
-      -> decltype(this->CallImpl(llvm::index_sequence_for<Args...>(),
+      -> decltype(this->CallImpl(std::index_sequence_for<Args...>(),
                                  std::forward<RestArgs>(Rest)...)) {
 
 #ifndef NDEBUG
     assert(!WasCalled && "Can only call result of Bind once.");
     WasCalled = true;
 #endif
-    return CallImpl(llvm::index_sequence_for<Args...>(),
+    return CallImpl(std::index_sequence_for<Args...>(),
                     std::forward<RestArgs>(Rest)...);
   }
 };
diff --git a/clang-tools-extra/clangd/unittests/Matchers.h b/clang-tools-extra/clangd/unittests/Matchers.h
index 0946398d8144..d477cf75e723 100644
--- a/clang-tools-extra/clangd/unittests/Matchers.h
+++ b/clang-tools-extra/clangd/unittests/Matchers.h
@@ -89,12 +89,12 @@ public:
 
   template <typename T> operator Matcher<const std::vector<T> &>() const {
     return ::testing::MakeMatcher(new SubsequenceMatcher<T>(
-        TypedMatchers<T>(llvm::index_sequence_for<M...>{})));
+        TypedMatchers<T>(std::index_sequence_for<M...>{})));
   }
 
 private:
   template <typename T, size_t... I>
-  std::vector<Matcher<T>> TypedMatchers(llvm::index_sequence<I...>) const {
+  std::vector<Matcher<T>> TypedMatchers(std::index_sequence<I...>) const {
     return {std::get<I>(Matchers)...};
   }
 };
diff --git a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
index 46e47a3100b5..ae7b9e7c3ee5 100644
--- a/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
+++ b/clang/include/clang/ASTMatchers/ASTMatchersInternal.h
@@ -1334,14 +1334,14 @@ public:
   template <typename T> operator Matcher<T>() const {
     return DynTypedMatcher::constructVariadic(
                Op, ast_type_traits::ASTNodeKind::getFromNodeKind<T>(),
-               getMatchers<T>(llvm::index_sequence_for<Ps...>()))
+               getMatchers<T>(std::index_sequence_for<Ps...>()))
         .template unconditionalConvertTo<T>();
   }
 
 private:
   // Helper method to unpack the tuple into a vector.
   template <typename T, std::size_t... Is>
-  std::vector<DynTypedMatcher> getMatchers(llvm::index_sequence<Is...>) const {
+  std::vector<DynTypedMatcher> getMatchers(std::index_sequence<Is...>) const {
     return {Matcher<T>(std::get<Is>(Params))...};
   }
 
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
index 4be2e5cdb96c..2dbb045be25c 100644
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -1621,7 +1621,7 @@ public:
 
     template <std::size_t... Is>
     void emit(const SemaDiagnosticBuilder &DB,
-              llvm::index_sequence<Is...>) const {
+              std::index_sequence<Is...>) const {
       // Apply all tuple elements to the builder in order.
       bool Dummy[] = {false, (DB << getPrintable(std::get<Is>(Args)))...};
       (void)Dummy;
@@ -1635,7 +1635,7 @@ public:
 
     void diagnose(Sema &S, SourceLocation Loc, QualType T) override {
       const SemaDiagnosticBuilder &DB = S.Diag(Loc, DiagID);
-      emit(DB, llvm::index_sequence_for<Ts...>());
+      emit(DB, std::index_sequence_for<Ts...>());
       DB << T;
     }
   };
diff --git a/clang/include/clang/Tooling/Refactoring/RefactoringActionRulesInternal.h b/clang/include/clang/Tooling/Refactoring/RefactoringActionRulesInternal.h
index aaa9e50faa9a..fb373fcf5029 100644
--- a/clang/include/clang/Tooling/Refactoring/RefactoringActionRulesInternal.h
+++ b/clang/include/clang/Tooling/Refactoring/RefactoringActionRulesInternal.h
@@ -47,7 +47,7 @@ template <typename RuleType, typename... RequirementTypes, size_t... Is>
 void invokeRuleAfterValidatingRequirements(
     RefactoringResultConsumer &Consumer, RefactoringRuleContext &Context,
     const std::tuple<RequirementTypes...> &Requirements,
-    llvm::index_sequence<Is...>) {
+    std::index_sequence<Is...>) {
   // Check if the requirements we're interested in can be evaluated.
   auto Values =
       std::make_tuple(std::get<Is>(Requirements).evaluate(Context)...);
@@ -87,7 +87,7 @@ template <typename... RequirementTypes, size_t... Is>
 void visitRefactoringOptions(
     RefactoringOptionVisitor &Visitor,
     const std::tuple<RequirementTypes...> &Requirements,
-    llvm::index_sequence<Is...>) {
+    std::index_sequence<Is...>) {
   visitRefactoringOptionsImpl(Visitor, std::get<Is>(Requirements)...);
 }
 
@@ -131,7 +131,7 @@ createRefactoringActionRule(const RequirementTypes &... Requirements) {
                 RefactoringRuleContext &Context) override {
       internal::invokeRuleAfterValidatingRequirements<RuleType>(
           Consumer, Context, Requirements,
-          llvm::index_sequence_for<RequirementTypes...>());
+          std::index_sequence_for<RequirementTypes...>());
     }
 
     bool hasSelectionRequirement() override {
@@ -142,7 +142,7 @@ createRefactoringActionRule(const RequirementTypes &... Requirements) {
     void visitRefactoringOptions(RefactoringOptionVisitor &Visitor) override {
       internal::visitRefactoringOptions(
           Visitor, Requirements,
-          llvm::index_sequence_for<RequirementTypes...>());
+          std::index_sequence_for<RequirementTypes...>());
     }
   private:
     std::tuple<RequirementTypes...> Requirements;
diff --git a/clang/lib/CodeGen/EHScopeStack.h b/clang/lib/CodeGen/EHScopeStack.h
index 3b0db35d982b..0ed67aabcd62 100644
--- a/clang/lib/CodeGen/EHScopeStack.h
+++ b/clang/lib/CodeGen/EHScopeStack.h
@@ -199,14 +199,14 @@ public:
     SavedTuple Saved;
 
     template <std::size_t... Is>
-    T restore(CodeGenFunction &CGF, llvm::index_sequence<Is...>) {
+    T restore(CodeGenFunction &CGF, std::index_sequence<Is...>) {
       // It's important that the restores are emitted in order. The braced init
       // list guarantees that.
       return T{DominatingValue<As>::restore(CGF, std::get<Is>(Saved))...};
     }
 
     void Emit(CodeGenFunction &CGF, Flags flags) override {
-      restore(CGF, llvm::index_sequence_for<As...>()).Emit(CGF, flags);
+      restore(CGF, std::index_sequence_for<As...>()).Emit(CGF, flags);
     }
 
   public:
diff --git a/llvm/include/llvm/ADT/STLExtras.h b/llvm/include/llvm/ADT/STLExtras.h
index 81dce0168c79..0e3911424a66 100644
--- a/llvm/include/llvm/ADT/STLExtras.h
+++ b/llvm/include/llvm/ADT/STLExtras.h
@@ -530,10 +530,6 @@ bool all_of(R &&range, UnaryPredicate P);
 template <typename R, typename UnaryPredicate>
 bool any_of(R &&range, UnaryPredicate P);
 
-template <size_t... I> struct index_sequence;
-
-template <class... Ts> struct index_sequence_for;
-
 namespace detail {
 
 using std::declval;
@@ -568,38 +564,38 @@ struct zip_common : public zip_traits<ZipType, Iters...> {
   std::tuple<Iters...> iterators;
 
 protected:
-  template <size_t... Ns> value_type deref(index_sequence<Ns...>) const {
+  template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
     return value_type(*std::get<Ns>(iterators)...);
   }
 
   template <size_t... Ns>
-  decltype(iterators) tup_inc(index_sequence<Ns...>) const {
+  decltype(iterators) tup_inc(std::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 {
+  decltype(iterators) tup_dec(std::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...>{}); }
+  value_type operator*() { return deref(std::index_sequence_for<Iters...>{}); }
 
   const value_type operator*() const {
-    return deref(index_sequence_for<Iters...>{});
+    return deref(std::index_sequence_for<Iters...>{});
   }
 
   ZipType &operator++() {
-    iterators = tup_inc(index_sequence_for<Iters...>{});
+    iterators = tup_inc(std::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...>{});
+    iterators = tup_dec(std::index_sequence_for<Iters...>{});
     return *reinterpret_cast<ZipType *>(this);
   }
 };
@@ -618,7 +614,8 @@ struct zip_first : public zip_common<zip_first<Iters...>, Iters...> {
 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 {
+  bool test(const zip_shortest<Iters...> &other,
+            std::index_sequence<Ns...>) const {
     return all_of(std::initializer_list<bool>{std::get<Ns>(this->iterators) !=
                                               std::get<Ns>(other.iterators)...},
                   identity<bool>{});
@@ -630,7 +627,7 @@ public:
   zip_shortest(Iters &&... ts) : Base(std::forward<Iters>(ts)...) {}
 
   bool operator==(const zip_shortest<Iters...> &other) const {
-    return !test(other, index_sequence_for<Iters...>{});
+    return !test(other, std::index_sequence_for<Iters...>{});
   }
 };
 
@@ -646,18 +643,21 @@ public:
 private:
   std::tuple<Args...> ts;
 
-  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) const {
+  template <size_t... Ns>
+  iterator begin_impl(std::index_sequence<Ns...>) const {
     return iterator(std::begin(std::get<Ns>(ts))...);
   }
-  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) const {
+  template <size_t... Ns> iterator end_impl(std::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...>{}); }
+  iterator begin() const {
+    return begin_impl(std::index_sequence_for<Args...>{});
+  }
+  iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
 };
 
 } // end namespace detail
@@ -727,20 +727,20 @@ private:
 
   template <size_t... Ns>
   bool test(const zip_longest_iterator<Iters...> &other,
-            index_sequence<Ns...>) const {
+            std::index_sequence<Ns...>) const {
     return llvm::any_of(
         std::initializer_list<bool>{std::get<Ns>(this->iterators) !=
                                     std::get<Ns>(other.iterators)...},
         identity<bool>{});
   }
 
-  template <size_t... Ns> value_type deref(index_sequence<Ns...>) const {
+  template <size_t... Ns> value_type deref(std::index_sequence<Ns...>) const {
     return value_type(
         deref_or_none(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
   }
 
   template <size_t... Ns>
-  decltype(iterators) tup_inc(index_sequence<Ns...>) const {
+  decltype(iterators) tup_inc(std::index_sequence<Ns...>) const {
     return std::tuple<Iters...>(
         next_or_end(std::get<Ns>(iterators), std::get<Ns>(end_iterators))...);
   }
@@ -750,17 +750,19 @@ public:
       : iterators(std::forward<Iters>(ts.first)...),
         end_iterators(std::forward<Iters>(ts.second)...) {}
 
-  value_type operator*() { return deref(index_sequence_for<Iters...>{}); }
+  value_type operator*() { return deref(std::index_sequence_for<Iters...>{}); }
 
-  value_type operator*() const { return deref(index_sequence_for<Iters...>{}); }
+  value_type operator*() const {
+    return deref(std::index_sequence_for<Iters...>{});
+  }
 
   zip_longest_iterator<Iters...> &operator++() {
-    iterators = tup_inc(index_sequence_for<Iters...>{});
+    iterators = tup_inc(std::index_sequence_for<Iters...>{});
     return *this;
   }
 
   bool operator==(const zip_longest_iterator<Iters...> &other) const {
-    return !test(other, index_sequence_for<Iters...>{});
+    return !test(other, std::index_sequence_for<Iters...>{});
   }
 };
 
@@ -777,12 +779,13 @@ public:
 private:
   std::tuple<Args...> ts;
 
-  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) const {
+  template <size_t... Ns>
+  iterator begin_impl(std::index_sequence<Ns...>) const {
     return iterator(std::make_pair(adl_begin(std::get<Ns>(ts)),
                                    adl_end(std::get<Ns>(ts)))...);
   }
 
-  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) const {
+  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) const {
     return iterator(std::make_pair(adl_end(std::get<Ns>(ts)),
                                    adl_end(std::get<Ns>(ts)))...);
   }
@@ -790,8 +793,10 @@ private:
 public:
   zip_longest_range(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...>{}); }
+  iterator begin() const {
+    return begin_impl(std::index_sequence_for<Args...>{});
+  }
+  iterator end() const { return end_impl(std::index_sequence_for<Args...>{}); }
 };
 } // namespace detail
 
@@ -847,7 +852,7 @@ class concat_iterator
   /// 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...>) {
+  template <size_t... Ns> void increment(std::index_sequence<Ns...>) {
     // Build a sequence of functions to increment each iterator if possible.
     bool (concat_iterator::*IncrementHelperFns[])() = {
         &concat_iterator::incrementHelper<Ns>...};
@@ -876,7 +881,7 @@ class concat_iterator
   /// reference.
   ///
   /// It is an error to call this with all iterators at the end.
-  template <size_t... Ns> ValueT &get(index_sequence<Ns...>) const {
+  template <size_t... Ns> ValueT &get(std::index_sequence<Ns...>) const {
     // Build a sequence of functions to get from iterator if possible.
     ValueT *(concat_iterator::*GetHelperFns[])() const = {
         &concat_iterator::getHelper<Ns>...};
@@ -901,11 +906,13 @@ public:
   using BaseT::operator++;
 
   concat_iterator &operator++() {
-    increment(index_sequence_for<IterTs...>());
+    increment(std::index_sequence_for<IterTs...>());
     return *this;
   }
 
-  ValueT &operator*() const { return get(index_sequence_for<IterTs...>()); }
+  ValueT &operator*() const {
+    return get(std::index_sequence_for<IterTs...>());
+  }
 
   bool operator==(const concat_iterator &RHS) const {
     return Begins == RHS.Begins && Ends == RHS.Ends;
@@ -928,10 +935,10 @@ public:
 private:
   std::tuple<RangeTs...> Ranges;
 
-  template <size_t... Ns> iterator begin_impl(index_sequence<Ns...>) {
+  template <size_t... Ns> iterator begin_impl(std::index_sequence<Ns...>) {
     return iterator(std::get<Ns>(Ranges)...);
   }
-  template <size_t... Ns> iterator end_impl(index_sequence<Ns...>) {
+  template <size_t... Ns> iterator end_impl(std::index_sequence<Ns...>) {
     return iterator(make_range(std::end(std::get<Ns>(Ranges)),
                                std::end(std::get<Ns>(Ranges)))...);
   }
@@ -940,8 +947,8 @@ 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...>{}); }
+  iterator begin() { return begin_impl(std::index_sequence_for<RangeTs...>{}); }
+  iterator end() { return end_impl(std::index_sequence_for<RangeTs...>{}); }
 };
 
 } // end namespace detail
@@ -990,28 +997,6 @@ struct on_first {
   }
 };
 
-// A subset of N3658. More stuff can be added as-needed.
-
-/// 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); }
-};
-
-/// 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...> {};
-
-/// 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> {};
@@ -1580,7 +1565,7 @@ template <typename R> detail::enumerator<R> enumerate(R &&TheRange) {
 namespace detail {
 
 template <typename F, typename Tuple, std::size_t... I>
-auto apply_tuple_impl(F &&f, Tuple &&t, index_sequence<I...>)
+auto apply_tuple_impl(F &&f, Tuple &&t, std::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))...);
 }
@@ -1593,9 +1578,9 @@ auto apply_tuple_impl(F &&f, Tuple &&t, index_sequence<I...>)
 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::make_index_sequence<
         std::tuple_size<typename std::decay<Tuple>::type>::value>{})) {
-  using Indices = build_index_impl<
+  using Indices = std::make_index_sequence<
       std::tuple_size<typename std::decay<Tuple>::type>::value>;
 
   return detail::apply_tuple_impl(std::forward<F>(f), std::forward<Tuple>(t),
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h b/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
index 07c7471afc6a..1892bf488251 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/RPCSerialization.h
@@ -551,26 +551,26 @@ public:
 
   /// RPC channel serialization for std::tuple.
   static Error serialize(ChannelT &C, const std::tuple<ArgTs...> &V) {
-    return serializeTupleHelper(C, V, llvm::index_sequence_for<ArgTs...>());
+    return serializeTupleHelper(C, V, std::index_sequence_for<ArgTs...>());
   }
 
   /// RPC channel deserialization for std::tuple.
   static Error deserialize(ChannelT &C, std::tuple<ArgTs...> &V) {
-    return deserializeTupleHelper(C, V, llvm::index_sequence_for<ArgTs...>());
+    return deserializeTupleHelper(C, V, std::index_sequence_for<ArgTs...>());
   }
 
 private:
   // Serialization helper for std::tuple.
   template <size_t... Is>
   static Error serializeTupleHelper(ChannelT &C, const std::tuple<ArgTs...> &V,
-                                    llvm::index_sequence<Is...> _) {
+                                    std::index_sequence<Is...> _) {
     return serializeSeq(C, std::get<Is>(V)...);
   }
 
   // Serialization helper for std::tuple.
   template <size_t... Is>
   static Error deserializeTupleHelper(ChannelT &C, std::tuple<ArgTs...> &V,
-                                      llvm::index_sequence<Is...> _) {
+                                      std::index_sequence<Is...> _) {
     return deserializeSeq(C, std::get<Is>(V)...);
   }
 };
diff --git a/llvm/include/llvm/ExecutionEngine/Orc/RPCUtils.h b/llvm/include/llvm/ExecutionEngine/Orc/RPCUtils.h
index 3b11e1b283de..1a8b2d14486c 100644
--- a/llvm/include/llvm/ExecutionEngine/Orc/RPCUtils.h
+++ b/llvm/include/llvm/ExecutionEngine/Orc/RPCUtils.h
@@ -502,7 +502,7 @@ public:
   static typename WrappedHandlerReturn<RetT>::Type
   unpackAndRun(HandlerT &Handler, std::tuple<TArgTs...> &Args) {
     return unpackAndRunHelper(Handler, Args,
-                              llvm::index_sequence_for<TArgTs...>());
+                              std::index_sequence_for<TArgTs...>());
   }
 
   // Call the given handler with the given arguments.
@@ -510,7 +510,7 @@ public:
   static Error unpackAndRunAsync(HandlerT &Handler, ResponderT &Responder,
                                  std::tuple<TArgTs...> &Args) {
     return unpackAndRunAsyncHelper(Handler, Responder, Args,
-                                   llvm::index_sequence_for<TArgTs...>());
+                                   std::index_sequence_for<TArgTs...>());
   }
 
   // Call the given handler with the given arguments.
@@ -540,14 +540,13 @@ public:
   // Deserialize arguments from the channel.
   template <typename ChannelT, typename... CArgTs>
   static Error deserializeArgs(ChannelT &C, std::tuple<CArgTs...> &Args) {
-    return deserializeArgsHelper(C, Args,
-                                 llvm::index_sequence_for<CArgTs...>());
+    return deserializeArgsHelper(C, Args, std::index_sequence_for<CArgTs...>());
   }
 
 private:
   template <typename ChannelT, typename... CArgTs, size_t... Indexes>
   static Error deserializeArgsHelper(ChannelT &C, std::tuple<CArgTs...> &Args,
-                                     llvm::index_sequence<Indexes...> _) {
+                                     std::index_sequence<Indexes...> _) {
     return SequenceSerialization<ChannelT, ArgTs...>::deserialize(
         C, std::get<Indexes>(Args)...);
   }
@@ -556,18 +555,16 @@ private:
   static typename WrappedHandlerReturn<
       typename HandlerTraits<HandlerT>::ReturnType>::Type
   unpackAndRunHelper(HandlerT &Handler, ArgTuple &Args,
-                     llvm::index_sequence<Indexes...>) {
+                     std::index_sequence<Indexes...>) {
     return run(Handler, std::move(std::get<Indexes>(Args))...);
   }
 
-
   template <typename HandlerT, typename ResponderT, typename ArgTuple,
             size_t... Indexes>
   static typename WrappedHandlerReturn<
       typename HandlerTraits<HandlerT>::ReturnType>::Type
   unpackAndRunAsyncHelper(HandlerT &Handler, ResponderT &Responder,
-                          ArgTuple &Args,
-                          llvm::index_sequence<Indexes...>) {
+                          ArgTuple &Args, std::index_sequence<Indexes...>) {
     return run(Handler, Responder, std::move(std::get<Indexes>(Args))...);
   }
 };
diff --git a/llvm/include/llvm/IR/PassManager.h b/llvm/include/llvm/IR/PassManager.h
index 37fe2a5b01ad..965c01b167cc 100644
--- a/llvm/include/llvm/IR/PassManager.h
+++ b/llvm/include/llvm/IR/PassManager.h
@@ -418,7 +418,7 @@ template <typename PassT, typename IRUnitT, typename AnalysisManagerT,
 typename PassT::Result
 getAnalysisResultUnpackTuple(AnalysisManagerT &AM, IRUnitT &IR,
                              std::tuple<ArgTs...> Args,
-                             llvm::index_sequence<Ns...>) {
+                             std::index_sequence<Ns...>) {
   (void)Args;
   return AM.template getResult<PassT>(IR, std::get<Ns>(Args)...);
 }
@@ -435,7 +435,7 @@ getAnalysisResult(AnalysisManager<IRUnitT, AnalysisArgTs...> &AM, IRUnitT &IR,
                   std::tuple<MainArgTs...> Args) {
   return (getAnalysisResultUnpackTuple<
           PassT, IRUnitT>)(AM, IR, Args,
-                           llvm::index_sequence_for<AnalysisArgTs...>{});
+                           std::index_sequence_for<AnalysisArgTs...>{});
 }
 
 } // namespace detail
diff --git a/llvm/include/llvm/Support/Format.h b/llvm/include/llvm/Support/Format.h
index 77dcbaebf1a3..9dd7b401b46a 100644
--- a/llvm/include/llvm/Support/Format.h
+++ b/llvm/include/llvm/Support/Format.h
@@ -29,6 +29,7 @@
 #include <cassert>
 #include <cstdio>
 #include <tuple>
+#include <utility>
 
 namespace llvm {
 
@@ -91,7 +92,7 @@ class format_object final : public format_object_base {
 
   template <std::size_t... Is>
   int snprint_tuple(char *Buffer, unsigned BufferSize,
-                    index_sequence<Is...>) const {
+                    std::index_sequence<Is...>) const {
 #ifdef _MSC_VER
     return _snprintf(Buffer, BufferSize, Fmt, std::get<Is>(Vals)...);
 #else
@@ -106,7 +107,7 @@ public:
   }
 
   int snprint(char *Buffer, unsigned BufferSize) const override {
-    return snprint_tuple(Buffer, BufferSize, index_sequence_for<Ts...>());
+    return snprint_tuple(Buffer, BufferSize, std::index_sequence_for<Ts...>());
   }
 };