text:
//===-- WinEHPrepare - Prepare exception handling for code generation ---===//
//
//                     The LLVM Compiler Infrastructure
//
// This file is distributed under the University of Illinois Open Source
// License. See LICENSE.TXT for details.
//
//===----------------------------------------------------------------------===//
//
// This pass lowers LLVM IR exception handling into something closer to what the
// backend wants. It snifs the personality function to see which kind of
// preparation is necessary. If the personality function uses the Itanium LSDA,
// this pass delegates to the DWARF EH preparation pass.
//
//===----------------------------------------------------------------------===//

#include "llvm/CodeGen/Passes.h"
#include "llvm/ADT/MapVector.h"
#include "llvm/ADT/STLExtras.h"
#include "llvm/ADT/SmallSet.h"
#include "llvm/ADT/TinyPtrVector.h"
#include "llvm/Analysis/LibCallSemantics.h"
#include "llvm/CodeGen/WinEHFuncInfo.h"
#include "llvm/IR/Dominators.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/IRBuilder.h"
#include "llvm/IR/Instructions.h"
#include "llvm/IR/IntrinsicInst.h"
#include "llvm/IR/Module.h"
#include "llvm/IR/PatternMatch.h"
#include "llvm/Pass.h"
#include "llvm/Support/CommandLine.h"
#include "llvm/Support/Debug.h"
#include "llvm/Support/raw_ostream.h"
#include "llvm/Transforms/Utils/BasicBlockUtils.h"
#include "llvm/Transforms/Utils/Cloning.h"
#include "llvm/Transforms/Utils/Local.h"
#include "llvm/Transforms/Utils/PromoteMemToReg.h"
#include <memory>

using namespace llvm;
using namespace llvm::PatternMatch;

#define DEBUG_TYPE "winehprepare"

namespace {

// This map is used to model frame variable usage during outlining, to
// construct a structure type to hold the frame variables in a frame
// allocation block, and to remap the frame variable allocas (including
// spill locations as needed) to GEPs that get the variable from the
// frame allocation structure.
typedef MapVector<Value *, TinyPtrVector<AllocaInst *>> FrameVarInfoMap;

// TinyPtrVector cannot hold nullptr, so we need our own sentinel that isn't
// quite null.
AllocaInst *getCatchObjectSentinel() {
  return static_cast<AllocaInst *>(nullptr) + 1;
}

typedef SmallSet<BasicBlock *, 4> VisitedBlockSet;

class LandingPadActions;
class LandingPadMap;

typedef DenseMap<const BasicBlock *, CatchHandler *> CatchHandlerMapTy;
typedef DenseMap<const BasicBlock *, CleanupHandler *> CleanupHandlerMapTy;

class WinEHPrepare : public FunctionPass {
public:
  static char ID; // Pass identification, replacement for typeid.
  WinEHPrepare(const TargetMachine *TM = nullptr)
      : FunctionPass(ID), DT(nullptr) {}

  bool runOnFunction(Function &Fn) override;

  bool doFinalization(Module &M) override;

  void getAnalysisUsage(AnalysisUsage &AU) const override;

  const char *getPassName() const override {
    return "Windows exception handling preparation";
  }

private:
  bool prepareExceptionHandlers(Function &F,
                                SmallVectorImpl<LandingPadInst *> &LPads);
  void promoteLandingPadValues(LandingPadInst *LPad);
  void completeNestedLandingPad(Function *ParentFn,
                                LandingPadInst *OutlinedLPad,
                                const LandingPadInst *OriginalLPad,
                                FrameVarInfoMap &VarInfo);
  bool outlineHandler(ActionHandler *Action, Function *SrcFn,
                      LandingPadInst *LPad, BasicBlock *StartBB,
                      FrameVarInfoMap &VarInfo);
  void addStubInvokeToHandlerIfNeeded(Function *Handler, Value *PersonalityFn);

  void mapLandingPadBlocks(LandingPadInst *LPad, LandingPadActions &Actions);
  CatchHandler *findCatchHandler(BasicBlock *BB, BasicBlock *&NextBB,
                                 VisitedBlockSet &VisitedBlocks);
  void findCleanupHandlers(LandingPadActions &Actions, BasicBlock *StartBB,
                           BasicBlock *EndBB);

  void processSEHCatchHandler(CatchHandler *Handler, BasicBlock *StartBB);

  // All fields are reset by runOnFunction.
  DominatorTree *DT;
  EHPersonality Personality;
  CatchHandlerMapTy CatchHandlerMap;
  CleanupHandlerMapTy CleanupHandlerMap;
  DenseMap<const LandingPadInst *, LandingPadMap> LPadMaps;

  // This maps landing pad instructions found in outlined handlers to
  // the landing pad instruction in the parent function from which they
  // were cloned.  The cloned/nested landing pad is used as the key
  // because the landing pad may be cloned into multiple handlers.
  // This map will be used to add the llvm.eh.actions call to the nested
  // landing pads after all handlers have been outlined.
  DenseMap<LandingPadInst *, const LandingPadInst *> NestedLPtoOriginalLP;

  // This maps blocks in the parent function which are destinations of
  // catch handlers to cloned blocks in (other) outlined handlers. This
  // handles the case where a nested landing pads has a catch handler that
  // returns to a handler function rather than the parent function.
  // The original block is used as the key here because there should only
  // ever be one handler function from which the cloned block is not pruned.
  // The original block will be pruned from the parent function after all
  // handlers have been outlined.  This map will be used to adjust the
  // return instructions of handlers which return to the block that was
  // outlined into a handler.  This is done after all handlers have been
  // outlined but before the outlined code is pruned from the parent function.
  DenseMap<const BasicBlock *, BasicBlock *> LPadTargetBlocks;
};

class WinEHFrameVariableMaterializer : public ValueMaterializer {
public:
  WinEHFrameVariableMaterializer(Function *OutlinedFn,
                                 FrameVarInfoMap &FrameVarInfo);
  ~WinEHFrameVariableMaterializer() override {}

  Value *materializeValueFor(Value *V) override;

  void escapeCatchObject(Value *V);

private:
  FrameVarInfoMap &FrameVarInfo;
  IRBuilder<> Builder;
};

class LandingPadMap {
public:
  LandingPadMap() : OriginLPad(nullptr) {}
  void mapLandingPad(const LandingPadInst *LPad);

  bool isInitialized() { return OriginLPad != nullptr; }

  bool isOriginLandingPadBlock(const BasicBlock *BB) const;
  bool isLandingPadSpecificInst(const Instruction *Inst) const;

  void remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
                     Value *SelectorValue) const;

private:
  const LandingPadInst *OriginLPad;
  // We will normally only see one of each of these instructions, but
  // if more than one occurs for some reason we can handle that.
  TinyPtrVector<const ExtractValueInst *> ExtractedEHPtrs;
  TinyPtrVector<const ExtractValueInst *> ExtractedSelectors;
};

class WinEHCloningDirectorBase : public CloningDirector {
public:
  WinEHCloningDirectorBase(Function *HandlerFn, FrameVarInfoMap &VarInfo,
                           LandingPadMap &LPadMap)
      : Materializer(HandlerFn, VarInfo),
        SelectorIDType(Type::getInt32Ty(HandlerFn->getContext())),
        Int8PtrType(Type::getInt8PtrTy(HandlerFn->getContext())),
        LPadMap(LPadMap) {}

  CloningAction handleInstruction(ValueToValueMapTy &VMap,
                                  const Instruction *Inst,
                                  BasicBlock *NewBB) override;

  virtual CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
                                         const Instruction *Inst,
                                         BasicBlock *NewBB) = 0;
  virtual CloningAction handleEndCatch(ValueToValueMapTy &VMap,
                                       const Instruction *Inst,
                                       BasicBlock *NewBB) = 0;
  virtual CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
                                        const Instruction *Inst,
                                        BasicBlock *NewBB) = 0;
  virtual CloningAction handleInvoke(ValueToValueMapTy &VMap,
                                     const InvokeInst *Invoke,
                                     BasicBlock *NewBB) = 0;
  virtual CloningAction handleResume(ValueToValueMapTy &VMap,
                                     const ResumeInst *Resume,
                                     BasicBlock *NewBB) = 0;
  virtual CloningAction handleLandingPad(ValueToValueMapTy &VMap,
                                         const LandingPadInst *LPad,
                                         BasicBlock *NewBB) = 0;

  ValueMaterializer *getValueMaterializer() override { return &Materializer; }

protected:
  WinEHFrameVariableMaterializer Materializer;
  Type *SelectorIDType;
  Type *Int8PtrType;
  LandingPadMap &LPadMap;
};

class WinEHCatchDirector : public WinEHCloningDirectorBase {
public:
  WinEHCatchDirector(
      Function *CatchFn, Value *Selector, FrameVarInfoMap &VarInfo,
      LandingPadMap &LPadMap,
      DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPads)
      : WinEHCloningDirectorBase(CatchFn, VarInfo, LPadMap),
        CurrentSelector(Selector->stripPointerCasts()),
        ExceptionObjectVar(nullptr), NestedLPtoOriginalLP(NestedLPads) {}

  CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
                                 const Instruction *Inst,
                                 BasicBlock *NewBB) override;
  CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
                               BasicBlock *NewBB) override;
  CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
                                const Instruction *Inst,
                                BasicBlock *NewBB) override;
  CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
                             BasicBlock *NewBB) override;
  CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
                             BasicBlock *NewBB) override;
  CloningAction handleLandingPad(ValueToValueMapTy &VMap,
                                 const LandingPadInst *LPad,
                                 BasicBlock *NewBB) override;

  Value *getExceptionVar() { return ExceptionObjectVar; }
  TinyPtrVector<BasicBlock *> &getReturnTargets() { return ReturnTargets; }

private:
  Value *CurrentSelector;

  Value *ExceptionObjectVar;
  TinyPtrVector<BasicBlock *> ReturnTargets;

  // This will be a reference to the field of the same name in the WinEHPrepare
  // object which instantiates this WinEHCatchDirector object.
  DenseMap<LandingPadInst *, const LandingPadInst *> &NestedLPtoOriginalLP;
};

class WinEHCleanupDirector : public WinEHCloningDirectorBase {
public:
  WinEHCleanupDirector(Function *CleanupFn, FrameVarInfoMap &VarInfo,
                       LandingPadMap &LPadMap)
      : WinEHCloningDirectorBase(CleanupFn, VarInfo, LPadMap) {}

  CloningAction handleBeginCatch(ValueToValueMapTy &VMap,
                                 const Instruction *Inst,
                                 BasicBlock *NewBB) override;
  CloningAction handleEndCatch(ValueToValueMapTy &VMap, const Instruction *Inst,
                               BasicBlock *NewBB) override;
  CloningAction handleTypeIdFor(ValueToValueMapTy &VMap,
                                const Instruction *Inst,
                                BasicBlock *NewBB) override;
  CloningAction handleInvoke(ValueToValueMapTy &VMap, const InvokeInst *Invoke,
                             BasicBlock *NewBB) override;
  CloningAction handleResume(ValueToValueMapTy &VMap, const ResumeInst *Resume,
                             BasicBlock *NewBB) override;
  CloningAction handleLandingPad(ValueToValueMapTy &VMap,
                                 const LandingPadInst *LPad,
                                 BasicBlock *NewBB) override;
};

class LandingPadActions {
public:
  LandingPadActions() : HasCleanupHandlers(false) {}

  void insertCatchHandler(CatchHandler *Action) { Actions.push_back(Action); }
  void insertCleanupHandler(CleanupHandler *Action) {
    Actions.push_back(Action);
    HasCleanupHandlers = true;
  }

  bool includesCleanup() const { return HasCleanupHandlers; }

  SmallVectorImpl<ActionHandler *> &actions() { return Actions; }
  SmallVectorImpl<ActionHandler *>::iterator begin() { return Actions.begin(); }
  SmallVectorImpl<ActionHandler *>::iterator end() { return Actions.end(); }

private:
  // Note that this class does not own the ActionHandler objects in this vector.
  // The ActionHandlers are owned by the CatchHandlerMap and CleanupHandlerMap
  // in the WinEHPrepare class.
  SmallVector<ActionHandler *, 4> Actions;
  bool HasCleanupHandlers;
};

} // end anonymous namespace

char WinEHPrepare::ID = 0;
INITIALIZE_TM_PASS(WinEHPrepare, "winehprepare", "Prepare Windows exceptions",
                   false, false)

FunctionPass *llvm::createWinEHPass(const TargetMachine *TM) {
  return new WinEHPrepare(TM);
}

// FIXME: Remove this once the backend can handle the prepared IR.
static cl::opt<bool>
    SEHPrepare("sehprepare", cl::Hidden,
               cl::desc("Prepare functions with SEH personalities"));

bool WinEHPrepare::runOnFunction(Function &Fn) {
  SmallVector<LandingPadInst *, 4> LPads;
  SmallVector<ResumeInst *, 4> Resumes;
  for (BasicBlock &BB : Fn) {
    if (auto *LP = BB.getLandingPadInst())
      LPads.push_back(LP);
    if (auto *Resume = dyn_cast<ResumeInst>(BB.getTerminator()))
      Resumes.push_back(Resume);
  }

  // No need to prepare functions that lack landing pads.
  if (LPads.empty())
    return false;

  // Classify the personality to see what kind of preparation we need.
  Personality = classifyEHPersonality(LPads.back()->getPersonalityFn());

  // Do nothing if this is not an MSVC personality.
  if (!isMSVCEHPersonality(Personality))
    return false;

  DT = &getAnalysis<DominatorTreeWrapperPass>().getDomTree();

  if (isAsynchronousEHPersonality(Personality) && !SEHPrepare) {
    // Replace all resume instructions with unreachable.
    // FIXME: Remove this once the backend can handle the prepared IR.
    for (ResumeInst *Resume : Resumes) {
      IRBuilder<>(Resume).CreateUnreachable();
      Resume->eraseFromParent();
    }
    return true;
  }

  // If there were any landing pads, prepareExceptionHandlers will make changes.
  prepareExceptionHandlers(Fn, LPads);
  return true;
}

bool WinEHPrepare::doFinalization(Module &M) { return false; }

void WinEHPrepare::getAnalysisUsage(AnalysisUsage &AU) const {
  AU.addRequired<DominatorTreeWrapperPass>();
}

bool WinEHPrepare::prepareExceptionHandlers(
    Function &F, SmallVectorImpl<LandingPadInst *> &LPads) {
  // These containers are used to re-map frame variables that are used in
  // outlined catch and cleanup handlers.  They will be populated as the
  // handlers are outlined.
  FrameVarInfoMap FrameVarInfo;

  bool HandlersOutlined = false;

  Module *M = F.getParent();
  LLVMContext &Context = M->getContext();

  // Create a new function to receive the handler contents.
  PointerType *Int8PtrType = Type::getInt8PtrTy(Context);
  Type *Int32Type = Type::getInt32Ty(Context);
  Function *ActionIntrin = Intrinsic::getDeclaration(M, Intrinsic::eh_actions);

  for (LandingPadInst *LPad : LPads) {
    // Look for evidence that this landingpad has already been processed.
    bool LPadHasActionList = false;
    BasicBlock *LPadBB = LPad->getParent();
    for (Instruction &Inst : *LPadBB) {
      if (auto *IntrinCall = dyn_cast<IntrinsicInst>(&Inst)) {
        if (IntrinCall->getIntrinsicID() == Intrinsic::eh_actions) {
          LPadHasActionList = true;
          break;
        }
      }
      // FIXME: This is here to help with the development of nested landing pad
      //        outlining.  It should be removed when that is finished.
      if (isa<UnreachableInst>(Inst)) {
        LPadHasActionList = true;
        break;
      }
    }

    // If we've already outlined the handlers for this landingpad,
    // there's nothing more to do here.
    if (LPadHasActionList)
      continue;

    // If either of the values in the aggregate returned by the landing pad is
    // extracted and stored to memory, promote the stored value to a register.
    promoteLandingPadValues(LPad);

    LandingPadActions Actions;
    mapLandingPadBlocks(LPad, Actions);

    HandlersOutlined |= !Actions.actions().empty();
    for (ActionHandler *Action : Actions) {
      if (Action->hasBeenProcessed())
        continue;
      BasicBlock *StartBB = Action->getStartBlock();

      // SEH doesn't do any outlining for catches. Instead, pass the handler
      // basic block addr to llvm.eh.actions and list the block as a return
      // target.
      if (isAsynchronousEHPersonality(Personality)) {
        if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
          processSEHCatchHandler(CatchAction, StartBB);
          continue;
        }
      }

      outlineHandler(Action, &F, LPad, StartBB, FrameVarInfo);
    }

    // Replace the landing pad with a new llvm.eh.action based landing pad.
    BasicBlock *NewLPadBB = BasicBlock::Create(Context, "lpad", &F, LPadBB);
    assert(!isa<PHINode>(LPadBB->begin()));
    auto *NewLPad = cast<LandingPadInst>(LPad->clone());
    NewLPadBB->getInstList().push_back(NewLPad);
    while (!pred_empty(LPadBB)) {
      auto *pred = *pred_begin(LPadBB);
      InvokeInst *Invoke = cast<InvokeInst>(pred->getTerminator());
      Invoke->setUnwindDest(NewLPadBB);
    }

    // If anyone is still using the old landingpad value, just give them undef
    // instead. The eh pointer and selector values are not real.
    LPad->replaceAllUsesWith(UndefValue::get(LPad->getType()));

    // Replace the mapping of any nested landing pad that previously mapped
    // to this landing pad with a referenced to the cloned version.
    for (auto &LPadPair : NestedLPtoOriginalLP) {
      const LandingPadInst *OriginalLPad = LPadPair.second;
      if (OriginalLPad == LPad) {
        LPadPair.second = NewLPad;
      }
    }

    // Replace uses of the old lpad in phis with this block and delete the old
    // block.
    LPadBB->replaceSuccessorsPhiUsesWith(NewLPadBB);
    LPadBB->getTerminator()->eraseFromParent();
    new UnreachableInst(LPadBB->getContext(), LPadBB);

    // Add a call to describe the actions for this landing pad.
    std::vector<Value *> ActionArgs;
    for (ActionHandler *Action : Actions) {
      // Action codes from docs are: 0 cleanup, 1 catch.
      if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
        ActionArgs.push_back(ConstantInt::get(Int32Type, 1));
        ActionArgs.push_back(CatchAction->getSelector());
        // Find the frame escape index of the exception object alloca in the
        // parent.
        int FrameEscapeIdx = -1;
        Value *EHObj = const_cast<Value *>(CatchAction->getExceptionVar());
        if (EHObj && !isa<ConstantPointerNull>(EHObj)) {
          auto I = FrameVarInfo.find(EHObj);
          assert(I != FrameVarInfo.end() &&
                 "failed to map llvm.eh.begincatch var");
          FrameEscapeIdx = std::distance(FrameVarInfo.begin(), I);
        }
        ActionArgs.push_back(ConstantInt::get(Int32Type, FrameEscapeIdx));
      } else {
        ActionArgs.push_back(ConstantInt::get(Int32Type, 0));
      }
      ActionArgs.push_back(Action->getHandlerBlockOrFunc());
    }
    CallInst *Recover =
        CallInst::Create(ActionIntrin, ActionArgs, "recover", NewLPadBB);

    // Add an indirect branch listing possible successors of the catch handlers.
    IndirectBrInst *Branch = IndirectBrInst::Create(Recover, 0, NewLPadBB);
    for (ActionHandler *Action : Actions) {
      if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
        for (auto *Target : CatchAction->getReturnTargets()) {
          Branch->addDestination(Target);
        }
      }
    }
  } // End for each landingpad

  // If nothing got outlined, there is no more processing to be done.
  if (!HandlersOutlined)
    return false;

  // Replace any nested landing pad stubs with the correct action handler.
  // This must be done before we remove unreachable blocks because it
  // cleans up references to outlined blocks that will be deleted.
  for (auto &LPadPair : NestedLPtoOriginalLP)
    completeNestedLandingPad(&F, LPadPair.first, LPadPair.second, FrameVarInfo);
  NestedLPtoOriginalLP.clear();

  F.addFnAttr("wineh-parent", F.getName());

  // Delete any blocks that were only used by handlers that were outlined above.
  removeUnreachableBlocks(F);

  BasicBlock *Entry = &F.getEntryBlock();
  IRBuilder<> Builder(F.getParent()->getContext());
  Builder.SetInsertPoint(Entry->getFirstInsertionPt());

  Function *FrameEscapeFn =
      Intrinsic::getDeclaration(M, Intrinsic::frameescape);
  Function *RecoverFrameFn =
      Intrinsic::getDeclaration(M, Intrinsic::framerecover);

  // Finally, replace all of the temporary allocas for frame variables used in
  // the outlined handlers with calls to llvm.framerecover.
  BasicBlock::iterator II = Entry->getFirstInsertionPt();
  Instruction *AllocaInsertPt = II;
  SmallVector<Value *, 8> AllocasToEscape;
  for (auto &VarInfoEntry : FrameVarInfo) {
    Value *ParentVal = VarInfoEntry.first;
    TinyPtrVector<AllocaInst *> &Allocas = VarInfoEntry.second;

    // If the mapped value isn't already an alloca, we need to spill it if it
    // is a computed value or copy it if it is an argument.
    AllocaInst *ParentAlloca = dyn_cast<AllocaInst>(ParentVal);
    if (!ParentAlloca) {
      if (auto *Arg = dyn_cast<Argument>(ParentVal)) {
        // Lower this argument to a copy and then demote that to the stack.
        // We can't just use the argument location because the handler needs
        // it to be in the frame allocation block.
        // Use 'select i8 true, %arg, undef' to simulate a 'no-op' instruction.
        Value *TrueValue = ConstantInt::getTrue(Context);
        Value *UndefValue = UndefValue::get(Arg->getType());
        Instruction *SI =
            SelectInst::Create(TrueValue, Arg, UndefValue,
                               Arg->getName() + ".tmp", AllocaInsertPt);
        Arg->replaceAllUsesWith(SI);
        // Reset the select operand, because it was clobbered by the RAUW above.
        SI->setOperand(1, Arg);
        ParentAlloca = DemoteRegToStack(*SI, true, SI);
      } else if (auto *PN = dyn_cast<PHINode>(ParentVal)) {
        ParentAlloca = DemotePHIToStack(PN, AllocaInsertPt);
      } else {
        Instruction *ParentInst = cast<Instruction>(ParentVal);
        // FIXME: This is a work-around to temporarily handle the case where an
        //        instruction that is only used in handlers is not sunk.
        //        Without uses, DemoteRegToStack would just eliminate the value.
        //        This will fail if ParentInst is an invoke.
        if (ParentInst->getNumUses() == 0) {
          BasicBlock::iterator InsertPt = ParentInst;
          ++InsertPt;
          ParentAlloca =
              new AllocaInst(ParentInst->getType(), nullptr,
                             ParentInst->getName() + ".reg2mem",
                             AllocaInsertPt);
          new StoreInst(ParentInst, ParentAlloca, InsertPt);
        } else {
          ParentAlloca = DemoteRegToStack(*ParentInst, true, AllocaInsertPt);
        }
      }
    }

    // FIXME: We should try to sink unescaped allocas from the parent frame into
    // the child frame. If the alloca is escaped, we have to use the lifetime
    // markers to ensure that the alloca is only live within the child frame.

    // Add this alloca to the list of things to escape.
    AllocasToEscape.push_back(ParentAlloca);

    // Next replace all outlined allocas that are mapped to it.
    for (AllocaInst *TempAlloca : Allocas) {
      if (TempAlloca == getCatchObjectSentinel())
        continue; // Skip catch parameter sentinels.
      Function *HandlerFn = TempAlloca->getParent()->getParent();
      // FIXME: Sink this GEP into the blocks where it is used.
      Builder.SetInsertPoint(TempAlloca);
      Builder.SetCurrentDebugLocation(TempAlloca->getDebugLoc());
      Value *RecoverArgs[] = {
          Builder.CreateBitCast(&F, Int8PtrType, ""),
          &(HandlerFn->getArgumentList().back()),
          llvm::ConstantInt::get(Int32Type, AllocasToEscape.size() - 1)};
      Value *RecoveredAlloca = Builder.CreateCall(RecoverFrameFn, RecoverArgs);
      // Add a pointer bitcast if the alloca wasn't an i8.
      if (RecoveredAlloca->getType() != TempAlloca->getType()) {
        RecoveredAlloca->setName(Twine(TempAlloca->getName()) + ".i8");
        RecoveredAlloca =
            Builder.CreateBitCast(RecoveredAlloca, TempAlloca->getType());
      }
      TempAlloca->replaceAllUsesWith(RecoveredAlloca);
      TempAlloca->removeFromParent();
      RecoveredAlloca->takeName(TempAlloca);
      delete TempAlloca;
    }
  } // End for each FrameVarInfo entry.

  // Insert 'call void (...)* @llvm.frameescape(...)' at the end of the entry
  // block.
  Builder.SetInsertPoint(&F.getEntryBlock().back());
  Builder.CreateCall(FrameEscapeFn, AllocasToEscape);

  // Clean up the handler action maps we created for this function
  DeleteContainerSeconds(CatchHandlerMap);
  CatchHandlerMap.clear();
  DeleteContainerSeconds(CleanupHandlerMap);
  CleanupHandlerMap.clear();

  return HandlersOutlined;
}

void WinEHPrepare::promoteLandingPadValues(LandingPadInst *LPad) {
  // If the return values of the landing pad instruction are extracted and
  // stored to memory, we want to promote the store locations to reg values.
  SmallVector<AllocaInst *, 2> EHAllocas;

  // The landingpad instruction returns an aggregate value.  Typically, its
  // value will be passed to a pair of extract value instructions and the
  // results of those extracts are often passed to store instructions.
  // In unoptimized code the stored value will often be loaded and then stored
  // again.
  for (auto *U : LPad->users()) {
    ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
    if (!Extract)
      continue;

    for (auto *EU : Extract->users()) {
      if (auto *Store = dyn_cast<StoreInst>(EU)) {
        auto *AV = cast<AllocaInst>(Store->getPointerOperand());
        EHAllocas.push_back(AV);
      }
    }
  }

  // We can't do this without a dominator tree.
  assert(DT);

  if (!EHAllocas.empty()) {
    PromoteMemToReg(EHAllocas, *DT);
    EHAllocas.clear();
  }

  // After promotion, some extracts may be trivially dead. Remove them.
  SmallVector<Value *, 4> Users(LPad->user_begin(), LPad->user_end());
  for (auto *U : Users)
    RecursivelyDeleteTriviallyDeadInstructions(U);
}

void WinEHPrepare::completeNestedLandingPad(Function *ParentFn,
                                            LandingPadInst *OutlinedLPad,
                                            const LandingPadInst *OriginalLPad,
                                            FrameVarInfoMap &FrameVarInfo) {
  // Get the nested block and erase the unreachable instruction that was
  // temporarily inserted as its terminator.
  LLVMContext &Context = ParentFn->getContext();
  BasicBlock *OutlinedBB = OutlinedLPad->getParent();
  assert(isa<UnreachableInst>(OutlinedBB->getTerminator()));
  OutlinedBB->getTerminator()->eraseFromParent();
  // That should leave OutlinedLPad as the last instruction in its block.
  assert(&OutlinedBB->back() == OutlinedLPad);

  // The original landing pad will have already had its action intrinsic
  // built by the outlining loop.  We need to clone that into the outlined
  // location.  It may also be necessary to add references to the exception
  // variables to the outlined handler in which this landing pad is nested
  // and remap return instructions in the nested handlers that should return
  // to an address in the outlined handler.
  Function *OutlinedHandlerFn = OutlinedBB->getParent();
  BasicBlock::const_iterator II = OriginalLPad;
  ++II;
  // The instruction after the landing pad should now be a call to eh.actions.
  const Instruction *Recover = II;
  assert(match(Recover, m_Intrinsic<Intrinsic::eh_actions>()));
  IntrinsicInst *EHActions = cast<IntrinsicInst>(Recover->clone());

  // Remap the exception variables into the outlined function.
  WinEHFrameVariableMaterializer Materializer(OutlinedHandlerFn, FrameVarInfo);
  SmallVector<BlockAddress *, 4> ActionTargets;
  SmallVector<ActionHandler *, 4> ActionList;
  parseEHActions(EHActions, ActionList);
  for (auto *Action : ActionList) {
    auto *Catch = dyn_cast<CatchHandler>(Action);
    if (!Catch)
      continue;
    // The dyn_cast to function here selects C++ catch handlers and skips
    // SEH catch handlers.
    auto *Handler = dyn_cast<Function>(Catch->getHandlerBlockOrFunc());
    if (!Handler)
      continue;
    // Visit all the return instructions, looking for places that return
    // to a location within OutlinedHandlerFn.
    for (BasicBlock &NestedHandlerBB : *Handler) {
      auto *Ret = dyn_cast<ReturnInst>(NestedHandlerBB.getTerminator());
      if (!Ret)
        continue;

      // Handler functions must always return a block address.
      BlockAddress *BA = cast<BlockAddress>(Ret->getReturnValue());
      // The original target will have been in the main parent function,
      // but if it is the address of a block that has been outlined, it
      // should be a block that was outlined into OutlinedHandlerFn.
      assert(BA->getFunction() == ParentFn);

      // Ignore targets that aren't part of OutlinedHandlerFn.
      if (!LPadTargetBlocks.count(BA->getBasicBlock()))
        continue;

      // If the return value is the address ofF a block that we
      // previously outlined into the parent handler function, replace
      // the return instruction and add the mapped target to the list
      // of possible return addresses.
      BasicBlock *MappedBB = LPadTargetBlocks[BA->getBasicBlock()];
      assert(MappedBB->getParent() == OutlinedHandlerFn);
      BlockAddress *NewBA = BlockAddress::get(OutlinedHandlerFn, MappedBB);
      Ret->eraseFromParent();
      ReturnInst::Create(Context, NewBA, &NestedHandlerBB);
      ActionTargets.push_back(NewBA);
    }
  }
  DeleteContainerPointers(ActionList);
  ActionList.clear();
  OutlinedBB->getInstList().push_back(EHActions);

  // Insert an indirect branch into the outlined landing pad BB.
  IndirectBrInst *IBr = IndirectBrInst::Create(EHActions, 0, OutlinedBB);
  // Add the previously collected action targets.
  for (auto *Target : ActionTargets)
    IBr->addDestination(Target->getBasicBlock());
}

// This function examines a block to determine whether the block ends with a
// conditional branch to a catch handler based on a selector comparison.
// This function is used both by the WinEHPrepare::findSelectorComparison() and
// WinEHCleanupDirector::handleTypeIdFor().
static bool isSelectorDispatch(BasicBlock *BB, BasicBlock *&CatchHandler,
                               Constant *&Selector, BasicBlock *&NextBB) {
  ICmpInst::Predicate Pred;
  BasicBlock *TBB, *FBB;
  Value *LHS, *RHS;

  if (!match(BB->getTerminator(),
             m_Br(m_ICmp(Pred, m_Value(LHS), m_Value(RHS)), TBB, FBB)))
    return false;

  if (!match(LHS,
             m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))) &&
      !match(RHS, m_Intrinsic<Intrinsic::eh_typeid_for>(m_Constant(Selector))))
    return false;

  if (Pred == CmpInst::ICMP_EQ) {
    CatchHandler = TBB;
    NextBB = FBB;
    return true;
  }

  if (Pred == CmpInst::ICMP_NE) {
    CatchHandler = FBB;
    NextBB = TBB;
    return true;
  }

  return false;
}

static BasicBlock *createStubLandingPad(Function *Handler,
                                        Value *PersonalityFn) {
  // FIXME: Finish this!
  LLVMContext &Context = Handler->getContext();
  BasicBlock *StubBB = BasicBlock::Create(Context, "stub");
  Handler->getBasicBlockList().push_back(StubBB);
  IRBuilder<> Builder(StubBB);
  LandingPadInst *LPad = Builder.CreateLandingPad(
      llvm::StructType::get(Type::getInt8PtrTy(Context),
                            Type::getInt32Ty(Context), nullptr),
      PersonalityFn, 0);
  LPad->setCleanup(true);
  Builder.CreateUnreachable();
  return StubBB;
}

// Cycles through the blocks in an outlined handler function looking for an
// invoke instruction and inserts an invoke of llvm.donothing with an empty
// landing pad if none is found.  The code that generates the .xdata tables for
// the handler needs at least one landing pad to identify the parent function's
// personality.
void WinEHPrepare::addStubInvokeToHandlerIfNeeded(Function *Handler,
                                                  Value *PersonalityFn) {
  ReturnInst *Ret = nullptr;
  for (BasicBlock &BB : *Handler) {
    TerminatorInst *Terminator = BB.getTerminator();
    // If we find an invoke, there is nothing to be done.
    auto *II = dyn_cast<InvokeInst>(Terminator);
    if (II)
      return;
    // If we've already recorded a return instruction, keep looking for invokes.
    if (Ret)
      continue;
    // If we haven't recorded a return instruction yet, try this terminator.
    Ret = dyn_cast<ReturnInst>(Terminator);
  }

  // If we got this far, the handler contains no invokes.  We should have seen
  // at least one return.  We'll insert an invoke of llvm.donothing ahead of
  // that return.
  assert(Ret);
  BasicBlock *OldRetBB = Ret->getParent();
  BasicBlock *NewRetBB = SplitBlock(OldRetBB, Ret);
  // SplitBlock adds an unconditional branch instruction at the end of the
  // parent block.  We want to replace that with an invoke call, so we can
  // erase it now.
  OldRetBB->getTerminator()->eraseFromParent();
  BasicBlock *StubLandingPad = createStubLandingPad(Handler, PersonalityFn);
  Function *F =
      Intrinsic::getDeclaration(Handler->getParent(), Intrinsic::donothing);
  InvokeInst::Create(F, NewRetBB, StubLandingPad, None, "", OldRetBB);
}

bool WinEHPrepare::outlineHandler(ActionHandler *Action, Function *SrcFn,
                                  LandingPadInst *LPad, BasicBlock *StartBB,
                                  FrameVarInfoMap &VarInfo) {
  Module *M = SrcFn->getParent();
  LLVMContext &Context = M->getContext();

  // Create a new function to receive the handler contents.
  Type *Int8PtrType = Type::getInt8PtrTy(Context);
  std::vector<Type *> ArgTys;
  ArgTys.push_back(Int8PtrType);
  ArgTys.push_back(Int8PtrType);
  Function *Handler;
  if (Action->getType() == Catch) {
    FunctionType *FnType = FunctionType::get(Int8PtrType, ArgTys, false);
    Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
                               SrcFn->getName() + ".catch", M);
  } else {
    FunctionType *FnType =
        FunctionType::get(Type::getVoidTy(Context), ArgTys, false);
    Handler = Function::Create(FnType, GlobalVariable::InternalLinkage,
                               SrcFn->getName() + ".cleanup", M);
  }

  Handler->addFnAttr("wineh-parent", SrcFn->getName());

  // Generate a standard prolog to setup the frame recovery structure.
  IRBuilder<> Builder(Context);
  BasicBlock *Entry = BasicBlock::Create(Context, "entry");
  Handler->getBasicBlockList().push_front(Entry);
  Builder.SetInsertPoint(Entry);
  Builder.SetCurrentDebugLocation(LPad->getDebugLoc());

  std::unique_ptr<WinEHCloningDirectorBase> Director;

  ValueToValueMapTy VMap;

  LandingPadMap &LPadMap = LPadMaps[LPad];
  if (!LPadMap.isInitialized())
    LPadMap.mapLandingPad(LPad);
  if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
    Constant *Sel = CatchAction->getSelector();
    Director.reset(new WinEHCatchDirector(Handler, Sel, VarInfo, LPadMap,
                                          NestedLPtoOriginalLP));
    LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
                          ConstantInt::get(Type::getInt32Ty(Context), 1));
  } else {
    Director.reset(new WinEHCleanupDirector(Handler, VarInfo, LPadMap));
    LPadMap.remapEHValues(VMap, UndefValue::get(Int8PtrType),
                          UndefValue::get(Type::getInt32Ty(Context)));
  }

  SmallVector<ReturnInst *, 8> Returns;
  ClonedCodeInfo OutlinedFunctionInfo;

  // If the start block contains PHI nodes, we need to map them.
  BasicBlock::iterator II = StartBB->begin();
  while (auto *PN = dyn_cast<PHINode>(II)) {
    bool Mapped = false;
    // Look for PHI values that we have already mapped (such as the selector).
    for (Value *Val : PN->incoming_values()) {
      if (VMap.count(Val)) {
        VMap[PN] = VMap[Val];
        Mapped = true;
      }
    }
    // If we didn't find a match for this value, map it as an undef.
    if (!Mapped) {
      VMap[PN] = UndefValue::get(PN->getType());
    }
    ++II;
  }

  // Skip over PHIs and, if applicable, landingpad instructions.
  II = StartBB->getFirstInsertionPt();

  CloneAndPruneIntoFromInst(Handler, SrcFn, II, VMap,
                            /*ModuleLevelChanges=*/false, Returns, "",
                            &OutlinedFunctionInfo, Director.get());

  // Move all the instructions in the first cloned block into our entry block.
  BasicBlock *FirstClonedBB = std::next(Function::iterator(Entry));
  Entry->getInstList().splice(Entry->end(), FirstClonedBB->getInstList());
  FirstClonedBB->eraseFromParent();

  // Make sure we can identify the handler's personality later.
  addStubInvokeToHandlerIfNeeded(Handler, LPad->getPersonalityFn());

  if (auto *CatchAction = dyn_cast<CatchHandler>(Action)) {
    WinEHCatchDirector *CatchDirector =
        reinterpret_cast<WinEHCatchDirector *>(Director.get());
    CatchAction->setExceptionVar(CatchDirector->getExceptionVar());
    CatchAction->setReturnTargets(CatchDirector->getReturnTargets());

    // Look for blocks that are not part of the landing pad that we just
    // outlined but terminate with a call to llvm.eh.endcatch and a
    // branch to a block that is in the handler we just outlined.
    // These blocks will be part of a nested landing pad that intends to
    // return to an address in this handler.  This case is best handled
    // after both landing pads have been outlined, so for now we'll just
    // save the association of the blocks in LPadTargetBlocks.  The
    // return instructions which are created from these branches will be
    // replaced after all landing pads have been outlined.
    for (const auto MapEntry : VMap) {
      // VMap maps all values and blocks that were just cloned, but dead
      // blocks which were pruned will map to nullptr.
      if (!isa<BasicBlock>(MapEntry.first) || MapEntry.second == nullptr)
        continue;
      const BasicBlock *MappedBB = cast<BasicBlock>(MapEntry.first);
      for (auto *Pred : predecessors(const_cast<BasicBlock *>(MappedBB))) {
        auto *Branch = dyn_cast<BranchInst>(Pred->getTerminator());
        if (!Branch || !Branch->isUnconditional() || Pred->size() <= 1)
          continue;
        BasicBlock::iterator II = const_cast<BranchInst *>(Branch);
        --II;
        if (match(cast<Value>(II), m_Intrinsic<Intrinsic::eh_endcatch>())) {
          // This would indicate that a nested landing pad wants to return
          // to a block that is outlined into two different handlers.
          assert(!LPadTargetBlocks.count(MappedBB));
          LPadTargetBlocks[MappedBB] = cast<BasicBlock>(MapEntry.second);
        }
      }
    }
  } // End if (CatchAction)

  Action->setHandlerBlockOrFunc(Handler);

  return true;
}

/// This BB must end in a selector dispatch. All we need to do is pass the
/// handler block to llvm.eh.actions and list it as a possible indirectbr
/// target.
void WinEHPrepare::processSEHCatchHandler(CatchHandler *CatchAction,
                                          BasicBlock *StartBB) {
  BasicBlock *HandlerBB;
  BasicBlock *NextBB;
  Constant *Selector;
  bool Res = isSelectorDispatch(StartBB, HandlerBB, Selector, NextBB);
  if (Res) {
    // If this was EH dispatch, this must be a conditional branch to the handler
    // block.
    // FIXME: Handle instructions in the dispatch block. Currently we drop them,
    // leading to crashes if some optimization hoists stuff here.
    assert(CatchAction->getSelector() && HandlerBB &&
           "expected catch EH dispatch");
  } else {
    // This must be a catch-all. Split the block after the landingpad.
    assert(CatchAction->getSelector()->isNullValue() && "expected catch-all");
    HandlerBB =
        StartBB->splitBasicBlock(StartBB->getFirstInsertionPt(), "catch.all");
  }
  CatchAction->setHandlerBlockOrFunc(BlockAddress::get(HandlerBB));
  TinyPtrVector<BasicBlock *> Targets(HandlerBB);
  CatchAction->setReturnTargets(Targets);
}

void LandingPadMap::mapLandingPad(const LandingPadInst *LPad) {
  // Each instance of this class should only ever be used to map a single
  // landing pad.
  assert(OriginLPad == nullptr || OriginLPad == LPad);

  // If the landing pad has already been mapped, there's nothing more to do.
  if (OriginLPad == LPad)
    return;

  OriginLPad = LPad;

  // The landingpad instruction returns an aggregate value.  Typically, its
  // value will be passed to a pair of extract value instructions and the
  // results of those extracts will have been promoted to reg values before
  // this routine is called.
  for (auto *U : LPad->users()) {
    const ExtractValueInst *Extract = dyn_cast<ExtractValueInst>(U);
    if (!Extract)
      continue;
    assert(Extract->getNumIndices() == 1 &&
           "Unexpected operation: extracting both landing pad values");
    unsigned int Idx = *(Extract->idx_begin());
    assert((Idx == 0 || Idx == 1) &&
           "Unexpected operation: extracting an unknown landing pad element");
    if (Idx == 0) {
      ExtractedEHPtrs.push_back(Extract);
    } else if (Idx == 1) {
      ExtractedSelectors.push_back(Extract);
    }
  }
}

bool LandingPadMap::isOriginLandingPadBlock(const BasicBlock *BB) const {
  return BB->getLandingPadInst() == OriginLPad;
}

bool LandingPadMap::isLandingPadSpecificInst(const Instruction *Inst) const {
  if (Inst == OriginLPad)
    return true;
  for (auto *Extract : ExtractedEHPtrs) {
    if (Inst == Extract)
      return true;
  }
  for (auto *Extract : ExtractedSelectors) {
    if (Inst == Extract)
      return true;
  }
  return false;
}

void LandingPadMap::remapEHValues(ValueToValueMapTy &VMap, Value *EHPtrValue,
                                  Value *SelectorValue) const {
  // Remap all landing pad extract instructions to the specified values.
  for (auto *Extract : ExtractedEHPtrs)
    VMap[Extract] = EHPtrValue;
  for (auto *Extract : ExtractedSelectors)
    VMap[Extract] = SelectorValue;
}

CloningDirector::CloningAction WinEHCloningDirectorBase::handleInstruction(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  // If this is one of the boilerplate landing pad instructions, skip it.
  // The instruction will have already been remapped in VMap.
  if (LPadMap.isLandingPadSpecificInst(Inst))
    return CloningDirector::SkipInstruction;

  // Nested landing pads will be cloned as stubs, with just the
  // landingpad instruction and an unreachable instruction. When
  // all landingpads have been outlined, we'll replace this with the
  // llvm.eh.actions call and indirect branch created when the
  // landing pad was outlined.
  if (auto *LPad = dyn_cast<LandingPadInst>(Inst)) {
    return handleLandingPad(VMap, LPad, NewBB);
  }

  if (auto *Invoke = dyn_cast<InvokeInst>(Inst))
    return handleInvoke(VMap, Invoke, NewBB);

  if (auto *Resume = dyn_cast<ResumeInst>(Inst))
    return handleResume(VMap, Resume, NewBB);

  if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
    return handleBeginCatch(VMap, Inst, NewBB);
  if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
    return handleEndCatch(VMap, Inst, NewBB);
  if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
    return handleTypeIdFor(VMap, Inst, NewBB);

  // Continue with the default cloning behavior.
  return CloningDirector::CloneInstruction;
}

CloningDirector::CloningAction WinEHCatchDirector::handleLandingPad(
    ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
  Instruction *NewInst = LPad->clone();
  if (LPad->hasName())
    NewInst->setName(LPad->getName());
  // Save this correlation for later processing.
  NestedLPtoOriginalLP[cast<LandingPadInst>(NewInst)] = LPad;
  VMap[LPad] = NewInst;
  BasicBlock::InstListType &InstList = NewBB->getInstList();
  InstList.push_back(NewInst);
  InstList.push_back(new UnreachableInst(NewBB->getContext()));
  return CloningDirector::StopCloningBB;
}

CloningDirector::CloningAction WinEHCatchDirector::handleBeginCatch(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  // The argument to the call is some form of the first element of the
  // landingpad aggregate value, but that doesn't matter.  It isn't used
  // here.
  // The second argument is an outparameter where the exception object will be
  // stored. Typically the exception object is a scalar, but it can be an
  // aggregate when catching by value.
  // FIXME: Leave something behind to indicate where the exception object lives
  // for this handler. Should it be part of llvm.eh.actions?
  assert(ExceptionObjectVar == nullptr && "Multiple calls to "
                                          "llvm.eh.begincatch found while "
                                          "outlining catch handler.");
  ExceptionObjectVar = Inst->getOperand(1)->stripPointerCasts();
  if (isa<ConstantPointerNull>(ExceptionObjectVar))
    return CloningDirector::SkipInstruction;
  assert(cast<AllocaInst>(ExceptionObjectVar)->isStaticAlloca() &&
         "catch parameter is not static alloca");
  Materializer.escapeCatchObject(ExceptionObjectVar);
  return CloningDirector::SkipInstruction;
}

CloningDirector::CloningAction
WinEHCatchDirector::handleEndCatch(ValueToValueMapTy &VMap,
                                   const Instruction *Inst, BasicBlock *NewBB) {
  auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
  // It might be interesting to track whether or not we are inside a catch
  // function, but that might make the algorithm more brittle than it needs
  // to be.

  // The end catch call can occur in one of two places: either in a
  // landingpad block that is part of the catch handlers exception mechanism,
  // or at the end of the catch block.  However, a catch-all handler may call
  // end catch from the original landing pad.  If the call occurs in a nested
  // landing pad block, we must skip it and continue so that the landing pad
  // gets cloned.
  auto *ParentBB = IntrinCall->getParent();
  if (ParentBB->isLandingPad() && !LPadMap.isOriginLandingPadBlock(ParentBB))
    return CloningDirector::SkipInstruction;

  // If an end catch occurs anywhere else we want to terminate the handler
  // with a return to the code that follows the endcatch call.  If the
  // next instruction is not an unconditional branch, we need to split the
  // block to provide a clear target for the return instruction.
  BasicBlock *ContinueBB;
  auto Next = std::next(BasicBlock::const_iterator(IntrinCall));
  const BranchInst *Branch = dyn_cast<BranchInst>(Next);
  if (!Branch || !Branch->isUnconditional()) {
    // We're interrupting the cloning process at this location, so the
    // const_cast we're doing here will not cause a problem.
    ContinueBB = SplitBlock(const_cast<BasicBlock *>(ParentBB),
                            const_cast<Instruction *>(cast<Instruction>(Next)));
  } else {
    ContinueBB = Branch->getSuccessor(0);
  }

  ReturnInst::Create(NewBB->getContext(), BlockAddress::get(ContinueBB), NewBB);
  ReturnTargets.push_back(ContinueBB);

  // We just added a terminator to the cloned block.
  // Tell the caller to stop processing the current basic block so that
  // the branch instruction will be skipped.
  return CloningDirector::StopCloningBB;
}

CloningDirector::CloningAction WinEHCatchDirector::handleTypeIdFor(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  auto *IntrinCall = dyn_cast<IntrinsicInst>(Inst);
  Value *Selector = IntrinCall->getArgOperand(0)->stripPointerCasts();
  // This causes a replacement that will collapse the landing pad CFG based
  // on the filter function we intend to match.
  if (Selector == CurrentSelector)
    VMap[Inst] = ConstantInt::get(SelectorIDType, 1);
  else
    VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
  // Tell the caller not to clone this instruction.
  return CloningDirector::SkipInstruction;
}

CloningDirector::CloningAction
WinEHCatchDirector::handleInvoke(ValueToValueMapTy &VMap,
                                 const InvokeInst *Invoke, BasicBlock *NewBB) {
  return CloningDirector::CloneInstruction;
}

CloningDirector::CloningAction
WinEHCatchDirector::handleResume(ValueToValueMapTy &VMap,
                                 const ResumeInst *Resume, BasicBlock *NewBB) {
  // Resume instructions shouldn't be reachable from catch handlers.
  // We still need to handle it, but it will be pruned.
  BasicBlock::InstListType &InstList = NewBB->getInstList();
  InstList.push_back(new UnreachableInst(NewBB->getContext()));
  return CloningDirector::StopCloningBB;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleLandingPad(
    ValueToValueMapTy &VMap, const LandingPadInst *LPad, BasicBlock *NewBB) {
  // The MS runtime will terminate the process if an exception occurs in a
  // cleanup handler, so we shouldn't encounter landing pads in the actual
  // cleanup code, but they may appear in catch blocks.  Depending on where
  // we started cloning we may see one, but it will get dropped during dead
  // block pruning.
  Instruction *NewInst = new UnreachableInst(NewBB->getContext());
  VMap[LPad] = NewInst;
  BasicBlock::InstListType &InstList = NewBB->getInstList();
  InstList.push_back(NewInst);
  return CloningDirector::StopCloningBB;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleBeginCatch(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  // Catch blocks within cleanup handlers will always be unreachable.
  // We'll insert an unreachable instruction now, but it will be pruned
  // before the cloning process is complete.
  BasicBlock::InstListType &InstList = NewBB->getInstList();
  InstList.push_back(new UnreachableInst(NewBB->getContext()));
  return CloningDirector::StopCloningBB;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleEndCatch(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  // Cleanup handlers nested within catch handlers may begin with a call to
  // eh.endcatch.  We can just ignore that instruction.
  return CloningDirector::SkipInstruction;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleTypeIdFor(
    ValueToValueMapTy &VMap, const Instruction *Inst, BasicBlock *NewBB) {
  // If we encounter a selector comparison while cloning a cleanup handler,
  // we want to stop cloning immediately.  Anything after the dispatch
  // will be outlined into a different handler.
  BasicBlock *CatchHandler;
  Constant *Selector;
  BasicBlock *NextBB;
  if (isSelectorDispatch(const_cast<BasicBlock *>(Inst->getParent()),
                         CatchHandler, Selector, NextBB)) {
    ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);
    return CloningDirector::StopCloningBB;
  }
  // If eg.typeid.for is called for any other reason, it can be ignored.
  VMap[Inst] = ConstantInt::get(SelectorIDType, 0);
  return CloningDirector::SkipInstruction;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleInvoke(
    ValueToValueMapTy &VMap, const InvokeInst *Invoke, BasicBlock *NewBB) {
  // All invokes in cleanup handlers can be replaced with calls.
  SmallVector<Value *, 16> CallArgs(Invoke->op_begin(), Invoke->op_end() - 3);
  // Insert a normal call instruction...
  CallInst *NewCall =
      CallInst::Create(const_cast<Value *>(Invoke->getCalledValue()), CallArgs,
                       Invoke->getName(), NewBB);
  NewCall->setCallingConv(Invoke->getCallingConv());
  NewCall->setAttributes(Invoke->getAttributes());
  NewCall->setDebugLoc(Invoke->getDebugLoc());
  VMap[Invoke] = NewCall;

  // Remap the operands.
  llvm::RemapInstruction(NewCall, VMap, RF_None, nullptr, &Materializer);

  // Insert an unconditional branch to the normal destination.
  BranchInst::Create(Invoke->getNormalDest(), NewBB);

  // The unwind destination won't be cloned into the new function, so
  // we don't need to clean up its phi nodes.

  // We just added a terminator to the cloned block.
  // Tell the caller to stop processing the current basic block.
  return CloningDirector::CloneSuccessors;
}

CloningDirector::CloningAction WinEHCleanupDirector::handleResume(
    ValueToValueMapTy &VMap, const ResumeInst *Resume, BasicBlock *NewBB) {
  ReturnInst::Create(NewBB->getContext(), nullptr, NewBB);

  // We just added a terminator to the cloned block.
  // Tell the caller to stop processing the current basic block so that
  // the branch instruction will be skipped.
  return CloningDirector::StopCloningBB;
}

WinEHFrameVariableMaterializer::WinEHFrameVariableMaterializer(
    Function *OutlinedFn, FrameVarInfoMap &FrameVarInfo)
    : FrameVarInfo(FrameVarInfo), Builder(OutlinedFn->getContext()) {
  BasicBlock *EntryBB = &OutlinedFn->getEntryBlock();
  Builder.SetInsertPoint(EntryBB, EntryBB->getFirstInsertionPt());
}

Value *WinEHFrameVariableMaterializer::materializeValueFor(Value *V) {
  // If we're asked to materialize a value that is an instruction, we
  // temporarily create an alloca in the outlined function and add this
  // to the FrameVarInfo map.  When all the outlining is complete, we'll
  // collect these into a structure, spilling non-alloca values in the
  // parent frame as necessary, and replace these temporary allocas with
  // GEPs referencing the frame allocation block.

  // If the value is an alloca, the mapping is direct.
  if (auto *AV = dyn_cast<AllocaInst>(V)) {
    AllocaInst *NewAlloca = dyn_cast<AllocaInst>(AV->clone());
    Builder.Insert(NewAlloca, AV->getName());
    FrameVarInfo[AV].push_back(NewAlloca);
    return NewAlloca;
  }

  // For other types of instructions or arguments, we need an alloca based on
  // the value's type and a load of the alloca.  The alloca will be replaced
  // by a GEP, but the load will stay.  In the parent function, the value will
  // be spilled to a location in the frame allocation block.
  if (isa<Instruction>(V) || isa<Argument>(V)) {
    AllocaInst *NewAlloca =
        Builder.CreateAlloca(V->getType(), nullptr, "eh.temp.alloca");
    FrameVarInfo[V].push_back(NewAlloca);
    LoadInst *NewLoad = Builder.CreateLoad(NewAlloca, V->getName() + ".reload");
    return NewLoad;
  }

  // Don't materialize other values.
  return nullptr;
}

void WinEHFrameVariableMaterializer::escapeCatchObject(Value *V) {
  // Catch parameter objects have to live in the parent frame. When we see a use
  // of a catch parameter, add a sentinel to the multimap to indicate that it's
  // used from another handler. This will prevent us from trying to sink the
  // alloca into the handler and ensure that the catch parameter is present in
  // the call to llvm.frameescape.
  FrameVarInfo[V].push_back(getCatchObjectSentinel());
}

// This function maps the catch and cleanup handlers that are reachable from the
// specified landing pad. The landing pad sequence will have this basic shape:
//
//  <cleanup handler>
//  <selector comparison>
//  <catch handler>
//  <cleanup handler>
//  <selector comparison>
//  <catch handler>
//  <cleanup handler>
//  ...
//
// Any of the cleanup slots may be absent.  The cleanup slots may be occupied by
// any arbitrary control flow, but all paths through the cleanup code must
// eventually reach the next selector comparison and no path can skip to a
// different selector comparisons, though some paths may terminate abnormally.
// Therefore, we will use a depth first search from the start of any given
// cleanup block and stop searching when we find the next selector comparison.
//
// If the landingpad instruction does not have a catch clause, we will assume
// that any instructions other than selector comparisons and catch handlers can
// be ignored.  In practice, these will only be the boilerplate instructions.
//
// The catch handlers may also have any control structure, but we are only
// interested in the start of the catch handlers, so we don't need to actually
// follow the flow of the catch handlers.  The start of the catch handlers can
// be located from the compare instructions, but they can be skipped in the
// flow by following the contrary branch.
void WinEHPrepare::mapLandingPadBlocks(LandingPadInst *LPad,
                                       LandingPadActions &Actions) {
  unsigned int NumClauses = LPad->getNumClauses();
  unsigned int HandlersFound = 0;
  BasicBlock *BB = LPad->getParent();

  DEBUG(dbgs() << "Mapping landing pad: " << BB->getName() << "\n");

  if (NumClauses == 0) {
    findCleanupHandlers(Actions, BB, nullptr);
    return;
  }

  VisitedBlockSet VisitedBlocks;

  while (HandlersFound != NumClauses) {
    BasicBlock *NextBB = nullptr;

    // See if the clause we're looking for is a catch-all.
    // If so, the catch begins immediately.
    if (isa<ConstantPointerNull>(LPad->getClause(HandlersFound))) {
      // The catch all must occur last.
      assert(HandlersFound == NumClauses - 1);

      // For C++ EH, check if there is any interesting cleanup code before we
      // begin the catch. This is important because cleanups cannot rethrow
      // exceptions but code called from catches can. For SEH, it isn't
      // important if some finally code before a catch-all is executed out of
      // line or after recovering from the exception.
      if (Personality == EHPersonality::MSVC_CXX)
        findCleanupHandlers(Actions, BB, BB);

      // Add the catch handler to the action list.
      CatchHandler *Action =
          new CatchHandler(BB, LPad->getClause(HandlersFound), nullptr);
      CatchHandlerMap[BB] = Action;
      Actions.insertCatchHandler(Action);
      DEBUG(dbgs() << "  Catch all handler at block " << BB->getName() << "\n");
      ++HandlersFound;

      // Once we reach a catch-all, don't expect to hit a resume instruction.
      BB = nullptr;
      break;
    }

    CatchHandler *CatchAction = findCatchHandler(BB, NextBB, VisitedBlocks);
    // See if there is any interesting code executed before the dispatch.
    findCleanupHandlers(Actions, BB, CatchAction->getStartBlock());

    assert(CatchAction);
    ++HandlersFound;

    // Add the catch handler to the action list.
    Actions.insertCatchHandler(CatchAction);
    DEBUG(dbgs() << "  Found catch dispatch in block "
                 << CatchAction->getStartBlock()->getName() << "\n");

    // Move on to the block after the catch handler.
    BB = NextBB;
  }

  // If we didn't wind up in a catch-all, see if there is any interesting code
  // executed before the resume.
  findCleanupHandlers(Actions, BB, BB);

  // It's possible that some optimization moved code into a landingpad that
  // wasn't
  // previously being used for cleanup.  If that happens, we need to execute
  // that
  // extra code from a cleanup handler.
  if (Actions.includesCleanup() && !LPad->isCleanup())
    LPad->setCleanup(true);
}

// This function searches starting with the input block for the next
// block that terminates with a branch whose condition is based on a selector
// comparison.  This may be the input block.  See the mapLandingPadBlocks
// comments for a discussion of control flow assumptions.
//
CatchHandler *WinEHPrepare::findCatchHandler(BasicBlock *BB,
                                             BasicBlock *&NextBB,
                                             VisitedBlockSet &VisitedBlocks) {
  // See if we've already found a catch handler use it.
  // Call count() first to avoid creating a null entry for blocks
  // we haven't seen before.
  if (CatchHandlerMap.count(BB) && CatchHandlerMap[BB] != nullptr) {
    CatchHandler *Action = cast<CatchHandler>(CatchHandlerMap[BB]);
    NextBB = Action->getNextBB();
    return Action;
  }

  // VisitedBlocks applies only to the current search.  We still
  // need to consider blocks that we've visited while mapping other
  // landing pads.
  VisitedBlocks.insert(BB);

  BasicBlock *CatchBlock = nullptr;
  Constant *Selector = nullptr;

  // If this is the first time we've visited this block from any landing pad
  // look to see if it is a selector dispatch block.
  if (!CatchHandlerMap.count(BB)) {
    if (isSelectorDispatch(BB, CatchBlock, Selector, NextBB)) {
      CatchHandler *Action = new CatchHandler(BB, Selector, NextBB);
      CatchHandlerMap[BB] = Action;
      return Action;
    }
  }

  // Visit each successor, looking for the dispatch.
  // FIXME: We expect to find the dispatch quickly, so this will probably
  //        work better as a breadth first search.
  for (BasicBlock *Succ : successors(BB)) {
    if (VisitedBlocks.count(Succ))
      continue;

    CatchHandler *Action = findCatchHandler(Succ, NextBB, VisitedBlocks);
    if (Action)
      return Action;
  }
  return nullptr;
}

// These are helper functions to combine repeated code from findCleanupHandlers.
static void createCleanupHandler(LandingPadActions &Actions,
                                 CleanupHandlerMapTy &CleanupHandlerMap,
                                 BasicBlock *BB) {
  CleanupHandler *Action = new CleanupHandler(BB);
  CleanupHandlerMap[BB] = Action;
  Actions.insertCleanupHandler(Action);
  DEBUG(dbgs() << "  Found cleanup code in block "
               << Action->getStartBlock()->getName() << "\n");
}

static bool isFrameAddressCall(Value *V) {
  return match(V, m_Intrinsic<Intrinsic::frameaddress>(m_SpecificInt(0)));
}

static CallSite matchOutlinedFinallyCall(BasicBlock *BB,
                                         Instruction *MaybeCall) {
  // Look for finally blocks that Clang has already outlined for us.
  //   %fp = call i8* @llvm.frameaddress(i32 0)
  //   call void @"fin$parent"(iN 1, i8* %fp)
  if (isFrameAddressCall(MaybeCall) && MaybeCall != BB->getTerminator())
    MaybeCall = MaybeCall->getNextNode();
  CallSite FinallyCall(MaybeCall);
  if (!FinallyCall || FinallyCall.arg_size() != 2)
    return CallSite();
  if (!match(FinallyCall.getArgument(0), m_SpecificInt(1)))
    return CallSite();
  if (!isFrameAddressCall(FinallyCall.getArgument(1)))
    return CallSite();
  return FinallyCall;
}

static BasicBlock *followSingleUnconditionalBranches(BasicBlock *BB) {
  // Skip single ubr blocks.
  while (BB->getFirstNonPHIOrDbg() == BB->getTerminator()) {
    auto *Br = dyn_cast<BranchInst>(BB->getTerminator());
    if (Br && Br->isUnconditional())
      BB = Br->getSuccessor(0);
    else
      return BB;
  }
  return BB;
}

// This function searches starting with the input block for the next block that
// contains code that is not part of a catch handler and would not be eliminated
// during handler outlining.
//
void WinEHPrepare::findCleanupHandlers(LandingPadActions &Actions,
                                       BasicBlock *StartBB, BasicBlock *EndBB) {
  // Here we will skip over the following:
  //
  // landing pad prolog:
  //
  // Unconditional branches
  //
  // Selector dispatch
  //
  // Resume pattern
  //
  // Anything else marks the start of an interesting block

  BasicBlock *BB = StartBB;
  // Anything other than an unconditional branch will kick us out of this loop
  // one way or another.
  while (BB) {
    BB = followSingleUnconditionalBranches(BB);
    // If we've already scanned this block, don't scan it again.  If it is
    // a cleanup block, there will be an action in the CleanupHandlerMap.
    // If we've scanned it and it is not a cleanup block, there will be a
    // nullptr in the CleanupHandlerMap.  If we have not scanned it, there will
    // be no entry in the CleanupHandlerMap.  We must call count() first to
    // avoid creating a null entry for blocks we haven't scanned.
    if (CleanupHandlerMap.count(BB)) {
      if (auto *Action = CleanupHandlerMap[BB]) {
        Actions.insertCleanupHandler(Action);
        DEBUG(dbgs() << "  Found cleanup code in block "
              << Action->getStartBlock()->getName() << "\n");
        // FIXME: This cleanup might chain into another, and we need to discover
        // that.
        return;
      } else {
        // Here we handle the case where the cleanup handler map contains a
        // value for this block but the value is a nullptr.  This means that
        // we have previously analyzed the block and determined that it did
        // not contain any cleanup code.  Based on the earlier analysis, we
        // know the the block must end in either an unconditional branch, a
        // resume or a conditional branch that is predicated on a comparison
        // with a selector.  Either the resume or the selector dispatch
        // would terminate the search for cleanup code, so the unconditional
        // branch is the only case for which we might need to continue
        // searching.
        BasicBlock *SuccBB = followSingleUnconditionalBranches(BB);
        if (SuccBB == BB || SuccBB == EndBB)
          return;
        BB = SuccBB;
        continue;
      }
    }

    // Create an entry in the cleanup handler map for this block.  Initially
    // we create an entry that says this isn't a cleanup block.  If we find
    // cleanup code, the caller will replace this entry.
    CleanupHandlerMap[BB] = nullptr;

    TerminatorInst *Terminator = BB->getTerminator();

    // Landing pad blocks have extra instructions we need to accept.
    LandingPadMap *LPadMap = nullptr;
    if (BB->isLandingPad()) {
      LandingPadInst *LPad = BB->getLandingPadInst();
      LPadMap = &LPadMaps[LPad];
      if (!LPadMap->isInitialized())
        LPadMap->mapLandingPad(LPad);
    }

    // Look for the bare resume pattern:
    //   %lpad.val1 = insertvalue { i8*, i32 } undef, i8* %exn, 0
    //   %lpad.val2 = insertvalue { i8*, i32 } %lpad.val1, i32 %sel, 1
    //   resume { i8*, i32 } %lpad.val2
    if (auto *Resume = dyn_cast<ResumeInst>(Terminator)) {
      InsertValueInst *Insert1 = nullptr;
      InsertValueInst *Insert2 = nullptr;
      Value *ResumeVal = Resume->getOperand(0);
      // If the resume value isn't a phi or landingpad value, it should be a
      // series of insertions. Identify them so we can avoid them when scanning
      // for cleanups.
      if (!isa<PHINode>(ResumeVal) && !isa<LandingPadInst>(ResumeVal)) {
        Insert2 = dyn_cast<InsertValueInst>(ResumeVal);
        if (!Insert2)
          return createCleanupHandler(Actions, CleanupHandlerMap, BB);
        Insert1 = dyn_cast<InsertValueInst>(Insert2->getAggregateOperand());
        if (!Insert1)
          return createCleanupHandler(Actions, CleanupHandlerMap, BB);
      }
      for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
           II != IE; ++II) {
        Instruction *Inst = II;
        if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
          continue;
        if (Inst == Insert1 || Inst == Insert2 || Inst == Resume)
          continue;
        if (!Inst->hasOneUse() ||
            (Inst->user_back() != Insert1 && Inst->user_back() != Insert2)) {
          return createCleanupHandler(Actions, CleanupHandlerMap, BB);
        }
      }
      return;
    }

    BranchInst *Branch = dyn_cast<BranchInst>(Terminator);
    if (Branch && Branch->isConditional()) {
      // Look for the selector dispatch.
      //   %2 = call i32 @llvm.eh.typeid.for(i8* bitcast (i8** @_ZTIf to i8*))
      //   %matches = icmp eq i32 %sel, %2
      //   br i1 %matches, label %catch14, label %eh.resume
      CmpInst *Compare = dyn_cast<CmpInst>(Branch->getCondition());
      if (!Compare || !Compare->isEquality())
        return createCleanupHandler(Actions, CleanupHandlerMap, BB);
      for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
           II != IE; ++II) {
        Instruction *Inst = II;
        if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
          continue;
        if (Inst == Compare || Inst == Branch)
          continue;
        if (match(Inst, m_Intrinsic<Intrinsic::eh_typeid_for>()))
          continue;
        return createCleanupHandler(Actions, CleanupHandlerMap, BB);
      }
      // The selector dispatch block should always terminate our search.
      assert(BB == EndBB);
      return;
    }

    if (isAsynchronousEHPersonality(Personality)) {
      // If this is a landingpad block, split the block at the first non-landing
      // pad instruction.
      Instruction *MaybeCall = BB->getFirstNonPHIOrDbg();
      if (LPadMap) {
        while (MaybeCall != BB->getTerminator() &&
               LPadMap->isLandingPadSpecificInst(MaybeCall))
          MaybeCall = MaybeCall->getNextNode();
      }

      // Look for outlined finally calls.
      if (CallSite FinallyCall = matchOutlinedFinallyCall(BB, MaybeCall)) {
        Function *Fin = FinallyCall.getCalledFunction();
        assert(Fin && "outlined finally call should be direct");
        auto *Action = new CleanupHandler(BB);
        Action->setHandlerBlockOrFunc(Fin);
        Actions.insertCleanupHandler(Action);
        CleanupHandlerMap[BB] = Action;
        DEBUG(dbgs() << "  Found frontend-outlined finally call to "
                     << Fin->getName() << " in block "
                     << Action->getStartBlock()->getName() << "\n");

        // Split the block if there were more interesting instructions and look
        // for finally calls in the normal successor block.
        BasicBlock *SuccBB = BB;
        if (FinallyCall.getInstruction() != BB->getTerminator() &&
            FinallyCall.getInstruction()->getNextNode() != BB->getTerminator()) {
          SuccBB = BB->splitBasicBlock(FinallyCall.getInstruction()->getNextNode());
        } else {
          if (FinallyCall.isInvoke()) {
            SuccBB = cast<InvokeInst>(FinallyCall.getInstruction())->getNormalDest();
          } else {
            SuccBB = BB->getUniqueSuccessor();
            assert(SuccBB && "splitOutlinedFinallyCalls didn't insert a branch");
          }
        }
        BB = SuccBB;
        if (BB == EndBB)
          return;
        continue;
      }
    }

    // Anything else is either a catch block or interesting cleanup code.
    for (BasicBlock::iterator II = BB->getFirstNonPHIOrDbg(), IE = BB->end();
         II != IE; ++II) {
      Instruction *Inst = II;
      if (LPadMap && LPadMap->isLandingPadSpecificInst(Inst))
        continue;
      // Unconditional branches fall through to this loop.
      if (Inst == Branch)
        continue;
      // If this is a catch block, there is no cleanup code to be found.
      if (match(Inst, m_Intrinsic<Intrinsic::eh_begincatch>()))
        return;
      // If this a nested landing pad, it may contain an endcatch call.
      if (match(Inst, m_Intrinsic<Intrinsic::eh_endcatch>()))
        return;
      // Anything else makes this interesting cleanup code.
      return createCleanupHandler(Actions, CleanupHandlerMap, BB);
    }

    // Only unconditional branches in empty blocks should get this far.
    assert(Branch && Branch->isUnconditional());
    if (BB == EndBB)
      return;
    BB = Branch->getSuccessor(0);
  }
}

// This is a public function, declared in WinEHFuncInfo.h and is also
// referenced by WinEHNumbering in FunctionLoweringInfo.cpp.
void llvm::parseEHActions(const IntrinsicInst *II,
                          SmallVectorImpl<ActionHandler *> &Actions) {
  for (unsigned I = 0, E = II->getNumArgOperands(); I != E;) {
    uint64_t ActionKind =
        cast<ConstantInt>(II->getArgOperand(I))->getZExtValue();
    if (ActionKind == /*catch=*/1) {
      auto *Selector = cast<Constant>(II->getArgOperand(I + 1));
      ConstantInt *EHObjIndex = cast<ConstantInt>(II->getArgOperand(I + 2));
      int64_t EHObjIndexVal = EHObjIndex->getSExtValue();
      Constant *Handler = cast<Constant>(II->getArgOperand(I + 3));
      I += 4;
      auto *CH = new CatchHandler(/*BB=*/nullptr, Selector, /*NextBB=*/nullptr);
      CH->setHandlerBlockOrFunc(Handler);
      CH->setExceptionVarIndex(EHObjIndexVal);
      Actions.push_back(CH);
    } else if (ActionKind == 0) {
      Constant *Handler = cast<Constant>(II->getArgOperand(I + 1));
      I += 2;
      auto *CH = new CleanupHandler(/*BB=*/nullptr);
      CH->setHandlerBlockOrFunc(Handler);
      Actions.push_back(CH);
    } else {
      llvm_unreachable("Expected either a catch or cleanup handler!");
    }
  }
  std::reverse(Actions.begin(), Actions.end());
}

redpajama_set_name: RedPajamaGithub


text:
How to Get Netflix Cheaper
No company has done more to revolutionize the way we consume TV shows and movies in the modern era than the California-based company, Netflix. Beginning way back in 1997 as an online DVD rental service, they switched over to being primarily an online streaming service in 2010.
Since then, they've grown into being not only the most popular out of the major streaming services, with over 200 million current subscribers worldwide, but also one of the biggest players in producing original TV shows and movies, including the likes of Stranger Things, Ozark, Enola Holmes, and Marriage Story.
Watch Netflix TV Shows
As the service has become more and more popular, Netflix has been able to increase the price of a Netflix subscription, which in turn has allowed them to keep on increasing their output of high-quality TV shows and movies.
Originally just a $7.99 monthly subscription cost for a standard Netflix account, which provides HD content on 2 devices at the same time, that price has now ballooned to $13.99 a month. Even the cost of the cheapest Netflix subscription, the Basic Netflix account, has seen an increase.
Getting Cheaper Netflix
If you want to watch Netflix, but long for the days of a more reasonably priced service, we're going to look into some of the best ways you can get Netflix cheaper right now.
And even though they discontinued their free one month trial last year, there is still a way to get free Netflix with a free trial. We'll look at how in part 2 with 'The 4 best ways to get cheap (or free) Netflix subscription plans'. But first, let's take a closer look at the different types of Netflix subscription currently available.
Which Netflix Subscription?
If you visit the Netflix website, you'll be given the choice of signing up to 3 different types of Netflix subscription, which you can watch via the Netflix app. The cheapest Netflix subscription, as we mentioned, is the basic Netflix account.
Basic Netflix Subscription
At $8.99 for this Netflix subscription this is the cheapest price you can get Netflix for. Although you still get full access to all the content on the streaming platform, the basic plan doesn't allow you to watch content in HD (high-definition) but only SD (standard definition). In technical terms, it's the difference between 1080p and 480p.
Although that may sound a lot, you may find yourself not even noticing the difference. Plus, if you're using a non-HD ready screen to watch Netflix, then the SD quality that comes with the basic Netflix subscription is all you would require.
This is also true if you have a low-speed internet connection, since SD content downloads at just 600 Kbps, whereas HD requires 6 Mbps (i.e. 10 times faster). So, if you're looking to save money, the basic Netflix account could be the one for you.
Standard Netflix Subscription
Perhaps the biggest reason why you might want to upgrade from the basic plan to the standard plan, aside from the HD content, is that with the standard Netflix subscription, you're able to watch on 2 devices at the same time..
This could make a huge difference if you have a family and plan to watch Netflix at the same time. Just like with regular TV, with the standard subscription you can watch the TV shows you like in one room, while your partner, or other family member watches the TV shows he or she likes in another room. This not only saves an awful lot of potential squabbling, it also helps with saving money on Netflix and even getting free Netflix, which we'll come to in part 2.
Premium Netflix Subscription
But if you want to watch Netflix in all its glory, and watch not just on one screen at the same time or even two, but four screens, then the Premium Netflix account is the one for you. With the premium plan, you and your whole family get to watch Netflix in incredible ultra HD, or 4K resolution. This is double the resolution of standard HD, with a much higher picture quality.
Though not every title on Netflix is available in ultra HD through their premium plans, there are still literally hundreds you can watch, and that number will only increase as they put out more TV shows and movies.
However, internet speed is a really important factor when considering whether or not to sign up for the premium Netflix subscription. It's recommended that you have a stable internet connection that can download at speeds of at least 25 Mbps.
Once you've decided which Netflix subscription is the right one for you, the next thing to look at is how you can save money with Netflix, and even get free Netflix through free trials.
The 4 Best Ways to Get Cheap (or Free) Netflix Subscription Plans
Before we come to our list, let's look at the claim you find on many website that you can get Netflix cheaper using online discounted gift cards.
The truth is that gift cards are a notoriously hit-or-miss affair, especially when it comes to a company like Netflix. Having discontinued their free trials, it seems that Netflix does everything it can to wipe the net of discounted Netflix gift cards too.
There is another option available when it comes to getting a Netflix gift card. However, it's not directly through Netflix itself and it's only available to current Netflix subscribers who pay through iTunes or Google Play.
Google Play gift cards and discounted iTunes gift cards are more readily available than their Netflix equivalents, though this still doesn't mean they're that easy to come by. Sites like CDKeys.com could offer you a couple of dollars off for discounted iTunes or Google Play gift cards if you're lucky enough to find them.
And another thing to bear in mind is that even current Netflix subscribers who pay this way can only do so as long as they're using their current credit or debit card. Once that runs out so does this option, and you'd then need to sign up directly through Netflix.
Let's start our list with a way to get the streaming service totally free…
1. T-Mobile Plan
Well…not exactly free. It does require that you're signed up to certain T-Mobile plans. But if you're already signed up to these plans, or switching to them is a viable option for you, then this is a great way to cut your Netflix bill to absolute zero.
The first of the free Netflix offers they provide is with their Magenta plan, holding a minimum of 2 lines, or their Magenta Max plan, holding just one line. If you have any of these then you get the Netflix Basic subscription included in your plan.
The second option gives you Netflix Standard for free. This is only available for users signed up to the T-Mobile Magenta Max plan, holding two or more lines.
When it comes to the monthly fee for these mobile plans, the Magenta plan costs $40 per line, and the Magenta Max plan $47 per line (at the time of writing).
2. DVD Rental Service
You may have known that Netflix started life as a DVD rental service before becoming the world's most popular streaming service. But did you know that they still run their DVD rental service to this day?
It's true, only the company is now called DVD.com, though it's still entirely run by Netflix. If you search cheapest Netflix subscription, you'll probably get the answer that it's Basic Netflix at $8.99. But technically speaking the cheapest Netflix subscription is a dollar less, at $7.99.
This is for the standard Netflix DVD plan, for which you can enjoy unlimited movies every month, with one DVD out at a time. And the best thing about renting DVDs from Netflix is that there are no late fees and all shipping is paid for.
If you'd rather enjoy 2 DVDs at a time, with everything else exactly the same, then you need to opt for the Premier plan at $11.99 a month.
Now the great thing about the Netflix DVD company is that they provide a month's free trial, something sadly lacking with their streaming service. However, you do need to provide payment details when registering. This means that if you don't want to continue paying when the free trial expires, be sure to cancel your account, which you can do at any time.
3. The Ol' VPN Hack
Now, this isn't really hacking, don't worry. But what it is is a way to trick Netflix into thinking you're in a different country than you really are.
Now why on earth would you want to do that? To answer this, we have to spill one of Netflix's sneakiest secrets: the price for a Netflix subscription varies from country to country. And not relatively, based on exchange rates, but in absolute terms. And by a lot!
Cheapest Country for Netflix
As we said, exchange rates are always changing and so too is the Netflix subscription pricing. At the time of writing, however, the cheapest Netflix country for the Basic and Standard subscriptions is Argentina, at around $3.28 and $5.40 a month respectively.
And for Netflix Premium, the cheapest country currently is Turkey, at $7.49 a month. These numbers alone (up to $10+ a month in savings) make it obvious why you would want to look into this method of getting a Netflix subscription. So, how can you make it work?
Setting it Up
The first thing you need to do is get a VPN (Virtual Private Network). This will change your IP (internet protocol) address, so that it's the same as your country of choice.
There are many options for which VPN to choose, so it's hard to say which is the best VPN . But some of the ones to take a look at are NordVPN, SurfShark, or ExpressVPN. You can compare prices and terms, but they should all do a good job of providing you with a fast, secure connection to your country of choice, for around $10 a month.
However, like most times you sign up for stuff on the web these days, Netflix requires new customers to provide a mobile number and send you an SMS to verify your account. And not actually being a native of Argentina or Turkey, chances are you don't have a mobile number for those countries. Thankfully, there are a couple of ways round this bump in the road.
Method 1: Find an online SMS site.
There are sites, such as smscodes.io, which let you create a virtual phone number in different countries. Once you've set this up, you can then successfully verify your Netflix account via SMS for that country. But you may have to spend a buck or two to get a number that actually works.
Method 2: Use an expired Netflix account.
If you have previously been a subscriber to Netflix, or if you're prepared to pay for a month of Netflix and then cancel your account, this method can work for you. Netflix only requires you to verify your account via SMS when you're setting up a new account. So if you're using an old one, this isn't necessary. All you need to do is turn on the VPN to Turkey or Argentina, then click to restart your subscription, and you can start using Netflix for that country.
Method 3: Set up a new account in your country first.
If neither of the first two options appeal, there's still one more way you can do it. First, follow all the steps to sign up for Netflix in your own country (including the SMS verification part). Then, as soon as you reach the screen to pay by credit card, turn on your VPN to Turkey or Argentina, refresh the page, and all prices should now be converted to Turkish Lira or Argentine Peso.
One thing that might jump out at you at this point is that if you're paying $10 a month for a VPN and getting just $10 a month in savings for your Netflix subscription, what's the point?
It's a good question. But it's worth considering that VPNs aren't just a great way to get cheaper Netflix, they're also one of the best ways you can ensure your online security, especially in this day and age of ever-increasing cyber attacks and government spying.
So, it's really up to you if you want to go with this option, or choose another method of getting cheaper, or even free Netflix, and start watching your favorite TV shows in no time. Let's look at some more hacks right now.
4. Share an Account
Method 1: Friends and Family
This is far and away the most common method used by people to lower the cost of streaming platform subscriptions, including of course Netflix. And it's potentially the cheapest way to go about it.
All in or out of the Family
The great thing about streaming services, including Netflix, is that outside of basic subscriptions, Netflix offers plans that allow users to watch on multiple devices at the same time. So, while you're watching your favorite TV shows, someone else using the same account can watch a movie on a different device.
Intended for people in the same household to be able to use the same account, Netflix thankfully is very cool about friends, colleagues, and other family members sharing an account, even if they don't live in the same household.
How much you can save
With the standard subscription you can watch on 2 devices simultaneously, which means you could split the $13.99 a month subscription price in half, and enjoy a saving a $6.98 a month.
But for even better savings, go all out and get the Premium subscription and three friends to share the cost. That way, the $17.99 a month price just got slashed to $4.50 a month, and you make a whopping $13.49-a-month saving!
But in this online age, why not make the process a whole lot easier and save yourself the trouble of potentially creating money squabbles among your friends?
Method 2: Online Sharing Community
There are online platforms, such as TogetherPrice, which allow people to form streaming account groups and set up payments between each other.
This is a great way to find people in the same boat as you fast, rather than having to ask among people in real life. But, like with everything on the web, you have to be careful with your online security. If you join up to one of the groups without a current Netflix subscription, you need to make a monthly payment to the Admin of the group (i.e. the person who holds the Netflix account).
If you're happy making private payments to individuals you don't know over the internet, then this method could be for you. If not, there is another alternative, which bypasses the need to make these kinds of payments altogether, and even gives you the chance of free Netflix!
Method 3: OneChannel
OneChannel brings together all of the benefits of account sharing of the previous two methods, allowing you to make big savings every month. But on top of that, it provides you with full online security and convenience via an easy=to-use app on your phone or tablet.
After you download and set up the OneChannel app, you can start streaming Netflix right away. All the hassle of matching up with other users and the potential security risk of organizing private payments online is removed.
How OneChannel works
You sign up to the platform as either an Admin (i.e. have a current Netflix account) or Guest (looking share an Admin's account). The software in the app matches you up with other users automatically and anonymously, so there's never any need to contact or share information with others.
Payments are made through the app rather than between users, ensuring total peace of mind for everyone involved. All credentials are encrypted and stored on the server, and regularly changed for extra security.
By allowing the OneChannel app to use the auto-fill function on your phone, whenever you log into the Netflix app, the username and passwords are automatically filled in. You then have full access to your own fully private, secure account with a personalized streaming history and recommendations.
Stream it all!
If you want to get cheaper Netflix, OneChannel is the way to go. But it's not just Netflix, you can sign up and start watching any or all of the 5 major streaming services: Netflix, Disney+, Amazon Prime Video, HBO Max, and Hulu. You'll now have a vast array of TV shows and movies you could start watching, all on one subscription!
And what's more, with OneChannel, you get a 7 day free trial – something that doesn't exist with any other service. And you don't need to worry about being charged automatically at the end of your 7 day free trial – no payment information is required to sign up. When the free trial is over, it's entirely up to you if you want to continue.
However, with savings of up to $40 a month, there's every reason to think you would want continue. But if you decide streaming isn't for you, you can cancel your account any time, no questions asked.
OneChannel for your viewing entertainment
You can download the OneChannel app now from the App Store or Google Play, completely free of charge. Get started on your Netflix journey today, save money, and enjoy the ride!
GET 7 DAYS FOR FREE
Enjoy more content for a fraction of the price
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