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diff --git a/clang/lib/CodeGen/CGCleanup.h b/clang/lib/CodeGen/CGCleanup.h
new file mode 100644
index 000000000000..ffe0f9d9dd20
--- /dev/null
+++ b/clang/lib/CodeGen/CGCleanup.h
@@ -0,0 +1,649 @@
+//===-- CGCleanup.h - Classes for cleanups IR generation --------*- C++ -*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+//
+// These classes support the generation of LLVM IR for cleanups.
+//
+//===----------------------------------------------------------------------===//
+
+#ifndef LLVM_CLANG_LIB_CODEGEN_CGCLEANUP_H
+#define LLVM_CLANG_LIB_CODEGEN_CGCLEANUP_H
+
+#include "EHScopeStack.h"
+
+#include "Address.h"
+#include "llvm/ADT/SmallPtrSet.h"
+#include "llvm/ADT/SmallVector.h"
+
+namespace llvm {
+class BasicBlock;
+class Value;
+class ConstantInt;
+class AllocaInst;
+}
+
+namespace clang {
+class FunctionDecl;
+namespace CodeGen {
+class CodeGenModule;
+class CodeGenFunction;
+
+/// The MS C++ ABI needs a pointer to RTTI data plus some flags to describe the
+/// type of a catch handler, so we use this wrapper.
+struct CatchTypeInfo {
+  llvm::Constant *RTTI;
+  unsigned Flags;
+};
+
+/// A protected scope for zero-cost EH handling.
+class EHScope {
+  llvm::BasicBlock *CachedLandingPad;
+  llvm::BasicBlock *CachedEHDispatchBlock;
+
+  EHScopeStack::stable_iterator EnclosingEHScope;
+
+  class CommonBitFields {
+    friend class EHScope;
+    unsigned Kind : 3;
+  };
+  enum { NumCommonBits = 3 };
+
+protected:
+  class CatchBitFields {
+    friend class EHCatchScope;
+    unsigned : NumCommonBits;
+
+    unsigned NumHandlers : 32 - NumCommonBits;
+  };
+
+  class CleanupBitFields {
+    friend class EHCleanupScope;
+    unsigned : NumCommonBits;
+
+    /// Whether this cleanup needs to be run along normal edges.
+    unsigned IsNormalCleanup : 1;
+
+    /// Whether this cleanup needs to be run along exception edges.
+    unsigned IsEHCleanup : 1;
+
+    /// Whether this cleanup is currently active.
+    unsigned IsActive : 1;
+
+    /// Whether this cleanup is a lifetime marker
+    unsigned IsLifetimeMarker : 1;
+
+    /// Whether the normal cleanup should test the activation flag.
+    unsigned TestFlagInNormalCleanup : 1;
+
+    /// Whether the EH cleanup should test the activation flag.
+    unsigned TestFlagInEHCleanup : 1;
+
+    /// The amount of extra storage needed by the Cleanup.
+    /// Always a multiple of the scope-stack alignment.
+    unsigned CleanupSize : 12;
+  };
+
+  class FilterBitFields {
+    friend class EHFilterScope;
+    unsigned : NumCommonBits;
+
+    unsigned NumFilters : 32 - NumCommonBits;
+  };
+
+  union {
+    CommonBitFields CommonBits;
+    CatchBitFields CatchBits;
+    CleanupBitFields CleanupBits;
+    FilterBitFields FilterBits;
+  };
+
+public:
+  enum Kind { Cleanup, Catch, Terminate, Filter, PadEnd };
+
+  EHScope(Kind kind, EHScopeStack::stable_iterator enclosingEHScope)
+    : CachedLandingPad(nullptr), CachedEHDispatchBlock(nullptr),
+      EnclosingEHScope(enclosingEHScope) {
+    CommonBits.Kind = kind;
+  }
+
+  Kind getKind() const { return static_cast<Kind>(CommonBits.Kind); }
+
+  llvm::BasicBlock *getCachedLandingPad() const {
+    return CachedLandingPad;
+  }
+
+  void setCachedLandingPad(llvm::BasicBlock *block) {
+    CachedLandingPad = block;
+  }
+
+  llvm::BasicBlock *getCachedEHDispatchBlock() const {
+    return CachedEHDispatchBlock;
+  }
+
+  void setCachedEHDispatchBlock(llvm::BasicBlock *block) {
+    CachedEHDispatchBlock = block;
+  }
+
+  bool hasEHBranches() const {
+    if (llvm::BasicBlock *block = getCachedEHDispatchBlock())
+      return !block->use_empty();
+    return false;
+  }
+
+  EHScopeStack::stable_iterator getEnclosingEHScope() const {
+    return EnclosingEHScope;
+  }
+};
+
+/// A scope which attempts to handle some, possibly all, types of
+/// exceptions.
+///
+/// Objective C \@finally blocks are represented using a cleanup scope
+/// after the catch scope.
+class EHCatchScope : public EHScope {
+  // In effect, we have a flexible array member
+  //   Handler Handlers[0];
+  // But that's only standard in C99, not C++, so we have to do
+  // annoying pointer arithmetic instead.
+
+public:
+  struct Handler {
+    /// A type info value, or null (C++ null, not an LLVM null pointer)
+    /// for a catch-all.
+    CatchTypeInfo Type;
+
+    /// The catch handler for this type.
+    llvm::BasicBlock *Block;
+
+    bool isCatchAll() const { return Type.RTTI == nullptr; }
+  };
+
+private:
+  friend class EHScopeStack;
+
+  Handler *getHandlers() {
+    return reinterpret_cast<Handler*>(this+1);
+  }
+
+  const Handler *getHandlers() const {
+    return reinterpret_cast<const Handler*>(this+1);
+  }
+
+public:
+  static size_t getSizeForNumHandlers(unsigned N) {
+    return sizeof(EHCatchScope) + N * sizeof(Handler);
+  }
+
+  EHCatchScope(unsigned numHandlers,
+               EHScopeStack::stable_iterator enclosingEHScope)
+    : EHScope(Catch, enclosingEHScope) {
+    CatchBits.NumHandlers = numHandlers;
+    assert(CatchBits.NumHandlers == numHandlers && "NumHandlers overflow?");
+  }
+
+  unsigned getNumHandlers() const {
+    return CatchBits.NumHandlers;
+  }
+
+  void setCatchAllHandler(unsigned I, llvm::BasicBlock *Block) {
+    setHandler(I, CatchTypeInfo{nullptr, 0}, Block);
+  }
+
+  void setHandler(unsigned I, llvm::Constant *Type, llvm::BasicBlock *Block) {
+    assert(I < getNumHandlers());
+    getHandlers()[I].Type = CatchTypeInfo{Type, 0};
+    getHandlers()[I].Block = Block;
+  }
+
+  void setHandler(unsigned I, CatchTypeInfo Type, llvm::BasicBlock *Block) {
+    assert(I < getNumHandlers());
+    getHandlers()[I].Type = Type;
+    getHandlers()[I].Block = Block;
+  }
+
+  const Handler &getHandler(unsigned I) const {
+    assert(I < getNumHandlers());
+    return getHandlers()[I];
+  }
+
+  // Clear all handler blocks.
+  // FIXME: it's better to always call clearHandlerBlocks in DTOR and have a
+  // 'takeHandler' or some such function which removes ownership from the
+  // EHCatchScope object if the handlers should live longer than EHCatchScope.
+  void clearHandlerBlocks() {
+    for (unsigned I = 0, N = getNumHandlers(); I != N; ++I)
+      delete getHandler(I).Block;
+  }
+
+  typedef const Handler *iterator;
+  iterator begin() const { return getHandlers(); }
+  iterator end() const { return getHandlers() + getNumHandlers(); }
+
+  static bool classof(const EHScope *Scope) {
+    return Scope->getKind() == Catch;
+  }
+};
+
+/// A cleanup scope which generates the cleanup blocks lazily.
+class alignas(8) EHCleanupScope : public EHScope {
+  /// The nearest normal cleanup scope enclosing this one.
+  EHScopeStack::stable_iterator EnclosingNormal;
+
+  /// The nearest EH scope enclosing this one.
+  EHScopeStack::stable_iterator EnclosingEH;
+
+  /// The dual entry/exit block along the normal edge.  This is lazily
+  /// created if needed before the cleanup is popped.
+  llvm::BasicBlock *NormalBlock;
+
+  /// An optional i1 variable indicating whether this cleanup has been
+  /// activated yet.
+  llvm::AllocaInst *ActiveFlag;
+
+  /// Extra information required for cleanups that have resolved
+  /// branches through them.  This has to be allocated on the side
+  /// because everything on the cleanup stack has be trivially
+  /// movable.
+  struct ExtInfo {
+    /// The destinations of normal branch-afters and branch-throughs.
+    llvm::SmallPtrSet<llvm::BasicBlock*, 4> Branches;
+
+    /// Normal branch-afters.
+    SmallVector<std::pair<llvm::BasicBlock*,llvm::ConstantInt*>, 4>
+      BranchAfters;
+  };
+  mutable struct ExtInfo *ExtInfo;
+
+  /// The number of fixups required by enclosing scopes (not including
+  /// this one).  If this is the top cleanup scope, all the fixups
+  /// from this index onwards belong to this scope.
+  unsigned FixupDepth;
+
+  struct ExtInfo &getExtInfo() {
+    if (!ExtInfo) ExtInfo = new struct ExtInfo();
+    return *ExtInfo;
+  }
+
+  const struct ExtInfo &getExtInfo() const {
+    if (!ExtInfo) ExtInfo = new struct ExtInfo();
+    return *ExtInfo;
+  }
+
+public:
+  /// Gets the size required for a lazy cleanup scope with the given
+  /// cleanup-data requirements.
+  static size_t getSizeForCleanupSize(size_t Size) {
+    return sizeof(EHCleanupScope) + Size;
+  }
+
+  size_t getAllocatedSize() const {
+    return sizeof(EHCleanupScope) + CleanupBits.CleanupSize;
+  }
+
+  EHCleanupScope(bool isNormal, bool isEH, bool isActive,
+                 unsigned cleanupSize, unsigned fixupDepth,
+                 EHScopeStack::stable_iterator enclosingNormal,
+                 EHScopeStack::stable_iterator enclosingEH)
+      : EHScope(EHScope::Cleanup, enclosingEH),
+        EnclosingNormal(enclosingNormal), NormalBlock(nullptr),
+        ActiveFlag(nullptr), ExtInfo(nullptr), FixupDepth(fixupDepth) {
+    CleanupBits.IsNormalCleanup = isNormal;
+    CleanupBits.IsEHCleanup = isEH;
+    CleanupBits.IsActive = isActive;
+    CleanupBits.IsLifetimeMarker = false;
+    CleanupBits.TestFlagInNormalCleanup = false;
+    CleanupBits.TestFlagInEHCleanup = false;
+    CleanupBits.CleanupSize = cleanupSize;
+
+    assert(CleanupBits.CleanupSize == cleanupSize && "cleanup size overflow");
+  }
+
+  void Destroy() {
+    delete ExtInfo;
+  }
+  // Objects of EHCleanupScope are not destructed. Use Destroy().
+  ~EHCleanupScope() = delete;
+
+  bool isNormalCleanup() const { return CleanupBits.IsNormalCleanup; }
+  llvm::BasicBlock *getNormalBlock() const { return NormalBlock; }
+  void setNormalBlock(llvm::BasicBlock *BB) { NormalBlock = BB; }
+
+  bool isEHCleanup() const { return CleanupBits.IsEHCleanup; }
+
+  bool isActive() const { return CleanupBits.IsActive; }
+  void setActive(bool A) { CleanupBits.IsActive = A; }
+
+  bool isLifetimeMarker() const { return CleanupBits.IsLifetimeMarker; }
+  void setLifetimeMarker() { CleanupBits.IsLifetimeMarker = true; }
+
+  bool hasActiveFlag() const { return ActiveFlag != nullptr; }
+  Address getActiveFlag() const {
+    return Address(ActiveFlag, CharUnits::One());
+  }
+  void setActiveFlag(Address Var) {
+    assert(Var.getAlignment().isOne());
+    ActiveFlag = cast<llvm::AllocaInst>(Var.getPointer());
+  }
+
+  void setTestFlagInNormalCleanup() {
+    CleanupBits.TestFlagInNormalCleanup = true;
+  }
+  bool shouldTestFlagInNormalCleanup() const {
+    return CleanupBits.TestFlagInNormalCleanup;
+  }
+
+  void setTestFlagInEHCleanup() {
+    CleanupBits.TestFlagInEHCleanup = true;
+  }
+  bool shouldTestFlagInEHCleanup() const {
+    return CleanupBits.TestFlagInEHCleanup;
+  }
+
+  unsigned getFixupDepth() const { return FixupDepth; }
+  EHScopeStack::stable_iterator getEnclosingNormalCleanup() const {
+    return EnclosingNormal;
+  }
+
+  size_t getCleanupSize() const { return CleanupBits.CleanupSize; }
+  void *getCleanupBuffer() { return this + 1; }
+
+  EHScopeStack::Cleanup *getCleanup() {
+    return reinterpret_cast<EHScopeStack::Cleanup*>(getCleanupBuffer());
+  }
+
+  /// True if this cleanup scope has any branch-afters or branch-throughs.
+  bool hasBranches() const { return ExtInfo && !ExtInfo->Branches.empty(); }
+
+  /// Add a branch-after to this cleanup scope.  A branch-after is a
+  /// branch from a point protected by this (normal) cleanup to a
+  /// point in the normal cleanup scope immediately containing it.
+  /// For example,
+  ///   for (;;) { A a; break; }
+  /// contains a branch-after.
+  ///
+  /// Branch-afters each have their own destination out of the
+  /// cleanup, guaranteed distinct from anything else threaded through
+  /// it.  Therefore branch-afters usually force a switch after the
+  /// cleanup.
+  void addBranchAfter(llvm::ConstantInt *Index,
+                      llvm::BasicBlock *Block) {
+    struct ExtInfo &ExtInfo = getExtInfo();
+    if (ExtInfo.Branches.insert(Block).second)
+      ExtInfo.BranchAfters.push_back(std::make_pair(Block, Index));
+  }
+
+  /// Return the number of unique branch-afters on this scope.
+  unsigned getNumBranchAfters() const {
+    return ExtInfo ? ExtInfo->BranchAfters.size() : 0;
+  }
+
+  llvm::BasicBlock *getBranchAfterBlock(unsigned I) const {
+    assert(I < getNumBranchAfters());
+    return ExtInfo->BranchAfters[I].first;
+  }
+
+  llvm::ConstantInt *getBranchAfterIndex(unsigned I) const {
+    assert(I < getNumBranchAfters());
+    return ExtInfo->BranchAfters[I].second;
+  }
+
+  /// Add a branch-through to this cleanup scope.  A branch-through is
+  /// a branch from a scope protected by this (normal) cleanup to an
+  /// enclosing scope other than the immediately-enclosing normal
+  /// cleanup scope.
+  ///
+  /// In the following example, the branch through B's scope is a
+  /// branch-through, while the branch through A's scope is a
+  /// branch-after:
+  ///   for (;;) { A a; B b; break; }
+  ///
+  /// All branch-throughs have a common destination out of the
+  /// cleanup, one possibly shared with the fall-through.  Therefore
+  /// branch-throughs usually don't force a switch after the cleanup.
+  ///
+  /// \return true if the branch-through was new to this scope
+  bool addBranchThrough(llvm::BasicBlock *Block) {
+    return getExtInfo().Branches.insert(Block).second;
+  }
+
+  /// Determines if this cleanup scope has any branch throughs.
+  bool hasBranchThroughs() const {
+    if (!ExtInfo) return false;
+    return (ExtInfo->BranchAfters.size() != ExtInfo->Branches.size());
+  }
+
+  static bool classof(const EHScope *Scope) {
+    return (Scope->getKind() == Cleanup);
+  }
+};
+// NOTE: there's a bunch of different data classes tacked on after an
+// EHCleanupScope. It is asserted (in EHScopeStack::pushCleanup*) that
+// they don't require greater alignment than ScopeStackAlignment. So,
+// EHCleanupScope ought to have alignment equal to that -- not more
+// (would be misaligned by the stack allocator), and not less (would
+// break the appended classes).
+static_assert(alignof(EHCleanupScope) == EHScopeStack::ScopeStackAlignment,
+              "EHCleanupScope expected alignment");
+
+/// An exceptions scope which filters exceptions thrown through it.
+/// Only exceptions matching the filter types will be permitted to be
+/// thrown.
+///
+/// This is used to implement C++ exception specifications.
+class EHFilterScope : public EHScope {
+  // Essentially ends in a flexible array member:
+  // llvm::Value *FilterTypes[0];
+
+  llvm::Value **getFilters() {
+    return reinterpret_cast<llvm::Value**>(this+1);
+  }
+
+  llvm::Value * const *getFilters() const {
+    return reinterpret_cast<llvm::Value* const *>(this+1);
+  }
+
+public:
+  EHFilterScope(unsigned numFilters)
+    : EHScope(Filter, EHScopeStack::stable_end()) {
+    FilterBits.NumFilters = numFilters;
+    assert(FilterBits.NumFilters == numFilters && "NumFilters overflow");
+  }
+
+  static size_t getSizeForNumFilters(unsigned numFilters) {
+    return sizeof(EHFilterScope) + numFilters * sizeof(llvm::Value*);
+  }
+
+  unsigned getNumFilters() const { return FilterBits.NumFilters; }
+
+  void setFilter(unsigned i, llvm::Value *filterValue) {
+    assert(i < getNumFilters());
+    getFilters()[i] = filterValue;
+  }
+
+  llvm::Value *getFilter(unsigned i) const {
+    assert(i < getNumFilters());
+    return getFilters()[i];
+  }
+
+  static bool classof(const EHScope *scope) {
+    return scope->getKind() == Filter;
+  }
+};
+
+/// An exceptions scope which calls std::terminate if any exception
+/// reaches it.
+class EHTerminateScope : public EHScope {
+public:
+  EHTerminateScope(EHScopeStack::stable_iterator enclosingEHScope)
+    : EHScope(Terminate, enclosingEHScope) {}
+  static size_t getSize() { return sizeof(EHTerminateScope); }
+
+  static bool classof(const EHScope *scope) {
+    return scope->getKind() == Terminate;
+  }
+};
+
+class EHPadEndScope : public EHScope {
+public:
+  EHPadEndScope(EHScopeStack::stable_iterator enclosingEHScope)
+      : EHScope(PadEnd, enclosingEHScope) {}
+  static size_t getSize() { return sizeof(EHPadEndScope); }
+
+  static bool classof(const EHScope *scope) {
+    return scope->getKind() == PadEnd;
+  }
+};
+
+/// A non-stable pointer into the scope stack.
+class EHScopeStack::iterator {
+  char *Ptr;
+
+  friend class EHScopeStack;
+  explicit iterator(char *Ptr) : Ptr(Ptr) {}
+
+public:
+  iterator() : Ptr(nullptr) {}
+
+  EHScope *get() const {
+    return reinterpret_cast<EHScope*>(Ptr);
+  }
+
+  EHScope *operator->() const { return get(); }
+  EHScope &operator*() const { return *get(); }
+
+  iterator &operator++() {
+    size_t Size;
+    switch (get()->getKind()) {
+    case EHScope::Catch:
+      Size = EHCatchScope::getSizeForNumHandlers(
+          static_cast<const EHCatchScope *>(get())->getNumHandlers());
+      break;
+
+    case EHScope::Filter:
+      Size = EHFilterScope::getSizeForNumFilters(
+          static_cast<const EHFilterScope *>(get())->getNumFilters());
+      break;
+
+    case EHScope::Cleanup:
+      Size = static_cast<const EHCleanupScope *>(get())->getAllocatedSize();
+      break;
+
+    case EHScope::Terminate:
+      Size = EHTerminateScope::getSize();
+      break;
+
+    case EHScope::PadEnd:
+      Size = EHPadEndScope::getSize();
+      break;
+    }
+    Ptr += llvm::alignTo(Size, ScopeStackAlignment);
+    return *this;
+  }
+
+  iterator next() {
+    iterator copy = *this;
+    ++copy;
+    return copy;
+  }
+
+  iterator operator++(int) {
+    iterator copy = *this;
+    operator++();
+    return copy;
+  }
+
+  bool encloses(iterator other) const { return Ptr >= other.Ptr; }
+  bool strictlyEncloses(iterator other) const { return Ptr > other.Ptr; }
+
+  bool operator==(iterator other) const { return Ptr == other.Ptr; }
+  bool operator!=(iterator other) const { return Ptr != other.Ptr; }
+};
+
+inline EHScopeStack::iterator EHScopeStack::begin() const {
+  return iterator(StartOfData);
+}
+
+inline EHScopeStack::iterator EHScopeStack::end() const {
+  return iterator(EndOfBuffer);
+}
+
+inline void EHScopeStack::popCatch() {
+  assert(!empty() && "popping exception stack when not empty");
+
+  EHCatchScope &scope = cast<EHCatchScope>(*begin());
+  InnermostEHScope = scope.getEnclosingEHScope();
+  deallocate(EHCatchScope::getSizeForNumHandlers(scope.getNumHandlers()));
+}
+
+inline void EHScopeStack::popTerminate() {
+  assert(!empty() && "popping exception stack when not empty");
+
+  EHTerminateScope &scope = cast<EHTerminateScope>(*begin());
+  InnermostEHScope = scope.getEnclosingEHScope();
+  deallocate(EHTerminateScope::getSize());
+}
+
+inline EHScopeStack::iterator EHScopeStack::find(stable_iterator sp) const {
+  assert(sp.isValid() && "finding invalid savepoint");
+  assert(sp.Size <= stable_begin().Size && "finding savepoint after pop");
+  return iterator(EndOfBuffer - sp.Size);
+}
+
+inline EHScopeStack::stable_iterator
+EHScopeStack::stabilize(iterator ir) const {
+  assert(StartOfData <= ir.Ptr && ir.Ptr <= EndOfBuffer);
+  return stable_iterator(EndOfBuffer - ir.Ptr);
+}
+
+/// The exceptions personality for a function.
+struct EHPersonality {
+  const char *PersonalityFn;
+
+  // If this is non-null, this personality requires a non-standard
+  // function for rethrowing an exception after a catchall cleanup.
+  // This function must have prototype void(void*).
+  const char *CatchallRethrowFn;
+
+  static const EHPersonality &get(CodeGenModule &CGM, const FunctionDecl *FD);
+  static const EHPersonality &get(CodeGenFunction &CGF);
+
+  static const EHPersonality GNU_C;
+  static const EHPersonality GNU_C_SJLJ;
+  static const EHPersonality GNU_C_SEH;
+  static const EHPersonality GNU_ObjC;
+  static const EHPersonality GNU_ObjC_SJLJ;
+  static const EHPersonality GNU_ObjC_SEH;
+  static const EHPersonality GNUstep_ObjC;
+  static const EHPersonality GNU_ObjCXX;
+  static const EHPersonality NeXT_ObjC;
+  static const EHPersonality GNU_CPlusPlus;
+  static const EHPersonality GNU_CPlusPlus_SJLJ;
+  static const EHPersonality GNU_CPlusPlus_SEH;
+  static const EHPersonality MSVC_except_handler;
+  static const EHPersonality MSVC_C_specific_handler;
+  static const EHPersonality MSVC_CxxFrameHandler3;
+  static const EHPersonality GNU_Wasm_CPlusPlus;
+
+  /// Does this personality use landingpads or the family of pad instructions
+  /// designed to form funclets?
+  bool usesFuncletPads() const {
+    return isMSVCPersonality() || isWasmPersonality();
+  }
+
+  bool isMSVCPersonality() const {
+    return this == &MSVC_except_handler || this == &MSVC_C_specific_handler ||
+           this == &MSVC_CxxFrameHandler3;
+  }
+
+  bool isWasmPersonality() const { return this == &GNU_Wasm_CPlusPlus; }
+
+  bool isMSVCXXPersonality() const { return this == &MSVC_CxxFrameHandler3; }
+};
+}
+}
+
+#endif