text: //===-- Verifier.cpp - Implement the Module Verifier -----------------------==//
  //
  // 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
  //
  //===----------------------------------------------------------------------===//
  //
  // This file defines the function verifier interface, that can be used for some
  // sanity checking of input to the system.
  //
  // Note that this does not provide full `Java style' security and verifications,
  // instead it just tries to ensure that code is well-formed.
  //
  //  * Both of a binary operator's parameters are of the same type
  //  * Verify that the indices of mem access instructions match other operands
  //  * Verify that arithmetic and other things are only performed on first-class
  //    types.  Verify that shifts & logicals only happen on integrals f.e.
  //  * All of the constants in a switch statement are of the correct type
  //  * The code is in valid SSA form
  //  * It should be illegal to put a label into any other type (like a structure)
  //    or to return one. [except constant arrays!]
  //  * Only phi nodes can be self referential: 'add i32 %0, %0 ; <int>:0' is bad
  //  * PHI nodes must have an entry for each predecessor, with no extras.
  //  * PHI nodes must be the first thing in a basic block, all grouped together
  //  * PHI nodes must have at least one entry
  //  * All basic blocks should only end with terminator insts, not contain them
  //  * The entry node to a function must not have predecessors
  //  * All Instructions must be embedded into a basic block
  //  * Functions cannot take a void-typed parameter
  //  * Verify that a function's argument list agrees with it's declared type.
  //  * It is illegal to specify a name for a void value.
  //  * It is illegal to have a internal global value with no initializer
  //  * It is illegal to have a ret instruction that returns a value that does not
  //    agree with the function return value type.
  //  * Function call argument types match the function prototype
  //  * A landing pad is defined by a landingpad instruction, and can be jumped to
  //    only by the unwind edge of an invoke instruction.
  //  * A landingpad instruction must be the first non-PHI instruction in the
  //    block.
  //  * Landingpad instructions must be in a function with a personality function.
  //  * All other things that are tested by asserts spread about the code...
  //
  //===----------------------------------------------------------------------===//
  
  #include "llvm/IR/Verifier.h"
  #include "llvm/ADT/APFloat.h"
  #include "llvm/ADT/APInt.h"
  #include "llvm/ADT/ArrayRef.h"
  #include "llvm/ADT/DenseMap.h"
  #include "llvm/ADT/MapVector.h"
  #include "llvm/ADT/Optional.h"
  #include "llvm/ADT/STLExtras.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/ADT/SmallSet.h"
  #include "llvm/ADT/SmallVector.h"
  #include "llvm/ADT/StringExtras.h"
  #include "llvm/ADT/StringMap.h"
  #include "llvm/ADT/StringRef.h"
  #include "llvm/ADT/Twine.h"
  #include "llvm/ADT/ilist.h"
  #include "llvm/BinaryFormat/Dwarf.h"
  #include "llvm/IR/Argument.h"
  #include "llvm/IR/Attributes.h"
  #include "llvm/IR/BasicBlock.h"
  #include "llvm/IR/CFG.h"
  #include "llvm/IR/CallingConv.h"
  #include "llvm/IR/Comdat.h"
  #include "llvm/IR/Constant.h"
  #include "llvm/IR/ConstantRange.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DataLayout.h"
  #include "llvm/IR/DebugInfo.h"
  #include "llvm/IR/DebugInfoMetadata.h"
  #include "llvm/IR/DebugLoc.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/Dominators.h"
  #include "llvm/IR/Function.h"
  #include "llvm/IR/GlobalAlias.h"
  #include "llvm/IR/GlobalValue.h"
  #include "llvm/IR/GlobalVariable.h"
  #include "llvm/IR/InlineAsm.h"
  #include "llvm/IR/InstVisitor.h"
  #include "llvm/IR/InstrTypes.h"
  #include "llvm/IR/Instruction.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/IntrinsicInst.h"
  #include "llvm/IR/Intrinsics.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Metadata.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/ModuleSlotTracker.h"
  #include "llvm/IR/PassManager.h"
  #include "llvm/IR/Statepoint.h"
  #include "llvm/IR/Type.h"
  #include "llvm/IR/Use.h"
  #include "llvm/IR/User.h"
  #include "llvm/IR/Value.h"
  #include "llvm/Pass.h"
  #include "llvm/Support/AtomicOrdering.h"
  #include "llvm/Support/Casting.h"
  #include "llvm/Support/CommandLine.h"
  #include "llvm/Support/Debug.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/MathExtras.h"
  #include "llvm/Support/raw_ostream.h"
  #include <algorithm>
  #include <cassert>
  #include <cstdint>
  #include <memory>
  #include <string>
  #include <utility>
  
  using namespace llvm;
  
  namespace llvm {
  
  struct VerifierSupport {
    raw_ostream *OS;
    const Module &M;
    ModuleSlotTracker MST;
    const DataLayout &DL;
    LLVMContext &Context;
  
    /// Track the brokenness of the module while recursively visiting.
    bool Broken = false;
    /// Broken debug info can be "recovered" from by stripping the debug info.
    bool BrokenDebugInfo = false;
    /// Whether to treat broken debug info as an error.
    bool TreatBrokenDebugInfoAsError = true;
  
    explicit VerifierSupport(raw_ostream *OS, const Module &M)
        : OS(OS), M(M), MST(&M), DL(M.getDataLayout()), Context(M.getContext()) {}
  
  private:
    void Write(const Module *M) {
      *OS << "; ModuleID = '" << M->getModuleIdentifier() << "'\n";
    }
  
    void Write(const Value *V) {
      if (V)
        Write(*V);
    }
  
    void Write(const Value &V) {
      if (isa<Instruction>(V)) {
        V.print(*OS, MST);
        *OS << '\n';
      } else {
        V.printAsOperand(*OS, true, MST);
        *OS << '\n';
      }
    }
  
    void Write(const Metadata *MD) {
      if (!MD)
        return;
      MD->print(*OS, MST, &M);
      *OS << '\n';
    }
  
    template <class T> void Write(const MDTupleTypedArrayWrapper<T> &MD) {
      Write(MD.get());
    }
  
    void Write(const NamedMDNode *NMD) {
      if (!NMD)
        return;
      NMD->print(*OS, MST);
      *OS << '\n';
    }
  
    void Write(Type *T) {
      if (!T)
        return;
      *OS << ' ' << *T;
    }
  
    void Write(const Comdat *C) {
      if (!C)
        return;
      *OS << *C;
    }
  
    void Write(const APInt *AI) {
      if (!AI)
        return;
      *OS << *AI << '\n';
    }
  
    void Write(const unsigned i) { *OS << i << '\n'; }
  
    template <typename T> void Write(ArrayRef<T> Vs) {
      for (const T &V : Vs)
        Write(V);
    }
  
    template <typename T1, typename... Ts>
    void WriteTs(const T1 &V1, const Ts &... Vs) {
      Write(V1);
      WriteTs(Vs...);
    }
  
    template <typename... Ts> void WriteTs() {}
  
  public:
    /// A check failed, so printout out the condition and the message.
    ///
    /// This provides a nice place to put a breakpoint if you want to see why
    /// something is not correct.
    void CheckFailed(const Twine &Message) {
      if (OS)
        *OS << Message << '\n';
      Broken = true;
    }
  
    /// A check failed (with values to print).
    ///
    /// This calls the Message-only version so that the above is easier to set a
    /// breakpoint on.
    template <typename T1, typename... Ts>
    void CheckFailed(const Twine &Message, const T1 &V1, const Ts &... Vs) {
      CheckFailed(Message);
      if (OS)
        WriteTs(V1, Vs...);
    }
  
    /// A debug info check failed.
    void DebugInfoCheckFailed(const Twine &Message) {
      if (OS)
        *OS << Message << '\n';
      Broken |= TreatBrokenDebugInfoAsError;
      BrokenDebugInfo = true;
    }
  
    /// A debug info check failed (with values to print).
    template <typename T1, typename... Ts>
    void DebugInfoCheckFailed(const Twine &Message, const T1 &V1,
                              const Ts &... Vs) {
      DebugInfoCheckFailed(Message);
      if (OS)
        WriteTs(V1, Vs...);
    }
  };
  
  } // namespace llvm
  
  namespace {
  
  class Verifier : public InstVisitor<Verifier>, VerifierSupport {
    friend class InstVisitor<Verifier>;
  
    DominatorTree DT;
  
    /// When verifying a basic block, keep track of all of the
    /// instructions we have seen so far.
    ///
    /// This allows us to do efficient dominance checks for the case when an
    /// instruction has an operand that is an instruction in the same block.
    SmallPtrSet<Instruction *, 16> InstsInThisBlock;
  
    /// Keep track of the metadata nodes that have been checked already.
    SmallPtrSet<const Metadata *, 32> MDNodes;
  
    /// Keep track which DISubprogram is attached to which function.
    DenseMap<const DISubprogram *, const Function *> DISubprogramAttachments;
  
    /// Track all DICompileUnits visited.
    SmallPtrSet<const Metadata *, 2> CUVisited;
  
    /// The result type for a landingpad.
    Type *LandingPadResultTy;
  
    /// Whether we've seen a call to @llvm.localescape in this function
    /// already.
    bool SawFrameEscape;
  
    /// Whether the current function has a DISubprogram attached to it.
    bool HasDebugInfo = false;
  
    /// Whether source was present on the first DIFile encountered in each CU.
    DenseMap<const DICompileUnit *, bool> HasSourceDebugInfo;
  
    /// Stores the count of how many objects were passed to llvm.localescape for a
    /// given function and the largest index passed to llvm.localrecover.
    DenseMap<Function *, std::pair<unsigned, unsigned>> FrameEscapeInfo;
  
    // Maps catchswitches and cleanuppads that unwind to siblings to the
    // terminators that indicate the unwind, used to detect cycles therein.
    MapVector<Instruction *, Instruction *> SiblingFuncletInfo;
  
    /// Cache of constants visited in search of ConstantExprs.
    SmallPtrSet<const Constant *, 32> ConstantExprVisited;
  
    /// Cache of declarations of the llvm.experimental.deoptimize.<ty> intrinsic.
    SmallVector<const Function *, 4> DeoptimizeDeclarations;
  
    // Verify that this GlobalValue is only used in this module.
    // This map is used to avoid visiting uses twice. We can arrive at a user
    // twice, if they have multiple operands. In particular for very large
    // constant expressions, we can arrive at a particular user many times.
    SmallPtrSet<const Value *, 32> GlobalValueVisited;
  
    // Keeps track of duplicate function argument debug info.
    SmallVector<const DILocalVariable *, 16> DebugFnArgs;
  
    TBAAVerifier TBAAVerifyHelper;
  
    void checkAtomicMemAccessSize(Type *Ty, const Instruction *I);
  
  public:
    explicit Verifier(raw_ostream *OS, bool ShouldTreatBrokenDebugInfoAsError,
                      const Module &M)
        : VerifierSupport(OS, M), LandingPadResultTy(nullptr),
          SawFrameEscape(false), TBAAVerifyHelper(this) {
      TreatBrokenDebugInfoAsError = ShouldTreatBrokenDebugInfoAsError;
    }
  
    bool hasBrokenDebugInfo() const { return BrokenDebugInfo; }
  
    bool verify(const Function &F) {
      assert(F.getParent() == &M &&
             "An instance of this class only works with a specific module!");
  
      // First ensure the function is well-enough formed to compute dominance
      // information, and directly compute a dominance tree. We don't rely on the
      // pass manager to provide this as it isolates us from a potentially
      // out-of-date dominator tree and makes it significantly more complex to run
      // this code outside of a pass manager.
      // FIXME: It's really gross that we have to cast away constness here.
      if (!F.empty())
        DT.recalculate(const_cast<Function &>(F));
  
      for (const BasicBlock &BB : F) {
        if (!BB.empty() && BB.back().isTerminator())
          continue;
  
        if (OS) {
          *OS << "Basic Block in function '" << F.getName()
              << "' does not have terminator!\n";
          BB.printAsOperand(*OS, true, MST);
          *OS << "\n";
        }
        return false;
      }
  
      Broken = false;
      // FIXME: We strip const here because the inst visitor strips const.
      visit(const_cast<Function &>(F));
      verifySiblingFuncletUnwinds();
      InstsInThisBlock.clear();
      DebugFnArgs.clear();
      LandingPadResultTy = nullptr;
      SawFrameEscape = false;
      SiblingFuncletInfo.clear();
  
      return !Broken;
    }
  
    /// Verify the module that this instance of \c Verifier was initialized with.
    bool verify() {
      Broken = false;
  
      // Collect all declarations of the llvm.experimental.deoptimize intrinsic.
      for (const Function &F : M)
        if (F.getIntrinsicID() == Intrinsic::experimental_deoptimize)
          DeoptimizeDeclarations.push_back(&F);
  
      // Now that we've visited every function, verify that we never asked to
      // recover a frame index that wasn't escaped.
      verifyFrameRecoverIndices();
      for (const GlobalVariable &GV : M.globals())
        visitGlobalVariable(GV);
  
      for (const GlobalAlias &GA : M.aliases())
        visitGlobalAlias(GA);
  
      for (const NamedMDNode &NMD : M.named_metadata())
        visitNamedMDNode(NMD);
  
      for (const StringMapEntry<Comdat> &SMEC : M.getComdatSymbolTable())
        visitComdat(SMEC.getValue());
  
      visitModuleFlags(M);
      visitModuleIdents(M);
      visitModuleCommandLines(M);
  
      verifyCompileUnits();
  
      verifyDeoptimizeCallingConvs();
      DISubprogramAttachments.clear();
      return !Broken;
    }
  
  private:
    // Verification methods...
    void visitGlobalValue(const GlobalValue &GV);
    void visitGlobalVariable(const GlobalVariable &GV);
    void visitGlobalAlias(const GlobalAlias &GA);
    void visitAliaseeSubExpr(const GlobalAlias &A, const Constant &C);
    void visitAliaseeSubExpr(SmallPtrSetImpl<const GlobalAlias *> &Visited,
                             const GlobalAlias &A, const Constant &C);
    void visitNamedMDNode(const NamedMDNode &NMD);
    void visitMDNode(const MDNode &MD);
    void visitMetadataAsValue(const MetadataAsValue &MD, Function *F);
    void visitValueAsMetadata(const ValueAsMetadata &MD, Function *F);
    void visitComdat(const Comdat &C);
    void visitModuleIdents(const Module &M);
    void visitModuleCommandLines(const Module &M);
    void visitModuleFlags(const Module &M);
    void visitModuleFlag(const MDNode *Op,
                         DenseMap<const MDString *, const MDNode *> &SeenIDs,
                         SmallVectorImpl<const MDNode *> &Requirements);
    void visitModuleFlagCGProfileEntry(const MDOperand &MDO);
    void visitFunction(const Function &F);
    void visitBasicBlock(BasicBlock &BB);
    void visitRangeMetadata(Instruction &I, MDNode *Range, Type *Ty);
    void visitDereferenceableMetadata(Instruction &I, MDNode *MD);
  
    template <class Ty> bool isValidMetadataArray(const MDTuple &N);
  #define HANDLE_SPECIALIZED_MDNODE_LEAF(CLASS) void visit##CLASS(const CLASS &N);
  #include "llvm/IR/Metadata.def"
    void visitDIScope(const DIScope &N);
    void visitDIVariable(const DIVariable &N);
    void visitDILexicalBlockBase(const DILexicalBlockBase &N);
    void visitDITemplateParameter(const DITemplateParameter &N);
  
    void visitTemplateParams(const MDNode &N, const Metadata &RawParams);
  
    // InstVisitor overrides...
    using InstVisitor<Verifier>::visit;
    void visit(Instruction &I);
  
    void visitTruncInst(TruncInst &I);
    void visitZExtInst(ZExtInst &I);
    void visitSExtInst(SExtInst &I);
    void visitFPTruncInst(FPTruncInst &I);
    void visitFPExtInst(FPExtInst &I);
    void visitFPToUIInst(FPToUIInst &I);
    void visitFPToSIInst(FPToSIInst &I);
    void visitUIToFPInst(UIToFPInst &I);
    void visitSIToFPInst(SIToFPInst &I);
    void visitIntToPtrInst(IntToPtrInst &I);
    void visitPtrToIntInst(PtrToIntInst &I);
    void visitBitCastInst(BitCastInst &I);
    void visitAddrSpaceCastInst(AddrSpaceCastInst &I);
    void visitPHINode(PHINode &PN);
    void visitCallBase(CallBase &Call);
    void visitUnaryOperator(UnaryOperator &U);
    void visitBinaryOperator(BinaryOperator &B);
    void visitICmpInst(ICmpInst &IC);
    void visitFCmpInst(FCmpInst &FC);
    void visitExtractElementInst(ExtractElementInst &EI);
    void visitInsertElementInst(InsertElementInst &EI);
    void visitShuffleVectorInst(ShuffleVectorInst &EI);
    void visitVAArgInst(VAArgInst &VAA) { visitInstruction(VAA); }
    void visitCallInst(CallInst &CI);
    void visitInvokeInst(InvokeInst &II);
    void visitGetElementPtrInst(GetElementPtrInst &GEP);
    void visitLoadInst(LoadInst &LI);
    void visitStoreInst(StoreInst &SI);
    void verifyDominatesUse(Instruction &I, unsigned i);
    void visitInstruction(Instruction &I);
    void visitTerminator(Instruction &I);
    void visitBranchInst(BranchInst &BI);
    void visitReturnInst(ReturnInst &RI);
    void visitSwitchInst(SwitchInst &SI);
    void visitIndirectBrInst(IndirectBrInst &BI);
    void visitCallBrInst(CallBrInst &CBI);
    void visitSelectInst(SelectInst &SI);
    void visitUserOp1(Instruction &I);
    void visitUserOp2(Instruction &I) { visitUserOp1(I); }
    void visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call);
    void visitConstrainedFPIntrinsic(ConstrainedFPIntrinsic &FPI);
    void visitDbgIntrinsic(StringRef Kind, DbgVariableIntrinsic &DII);
    void visitDbgLabelIntrinsic(StringRef Kind, DbgLabelInst &DLI);
    void visitAtomicCmpXchgInst(AtomicCmpXchgInst &CXI);
    void visitAtomicRMWInst(AtomicRMWInst &RMWI);
    void visitFenceInst(FenceInst &FI);
    void visitAllocaInst(AllocaInst &AI);
    void visitExtractValueInst(ExtractValueInst &EVI);
    void visitInsertValueInst(InsertValueInst &IVI);
    void visitEHPadPredecessors(Instruction &I);
    void visitLandingPadInst(LandingPadInst &LPI);
    void visitResumeInst(ResumeInst &RI);
    void visitCatchPadInst(CatchPadInst &CPI);
    void visitCatchReturnInst(CatchReturnInst &CatchReturn);
    void visitCleanupPadInst(CleanupPadInst &CPI);
    void visitFuncletPadInst(FuncletPadInst &FPI);
    void visitCatchSwitchInst(CatchSwitchInst &CatchSwitch);
    void visitCleanupReturnInst(CleanupReturnInst &CRI);
  
    void verifySwiftErrorCall(CallBase &Call, const Value *SwiftErrorVal);
    void verifySwiftErrorValue(const Value *SwiftErrorVal);
    void verifyMustTailCall(CallInst &CI);
    bool performTypeCheck(Intrinsic::ID ID, Function *F, Type *Ty, int VT,
                          unsigned ArgNo, std::string &Suffix);
    bool verifyAttributeCount(AttributeList Attrs, unsigned Params);
    void verifyAttributeTypes(AttributeSet Attrs, bool IsFunction,
                              const Value *V);
    void verifyParameterAttrs(AttributeSet Attrs, Type *Ty, const Value *V);
    void verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,
                             const Value *V, bool IsIntrinsic);
    void verifyFunctionMetadata(ArrayRef<std::pair<unsigned, MDNode *>> MDs);
  
    void visitConstantExprsRecursively(const Constant *EntryC);
    void visitConstantExpr(const ConstantExpr *CE);
    void verifyStatepoint(const CallBase &Call);
    void verifyFrameRecoverIndices();
    void verifySiblingFuncletUnwinds();
  
    void verifyFragmentExpression(const DbgVariableIntrinsic &I);
    template <typename ValueOrMetadata>
    void verifyFragmentExpression(const DIVariable &V,
                                  DIExpression::FragmentInfo Fragment,
                                  ValueOrMetadata *Desc);
    void verifyFnArgs(const DbgVariableIntrinsic &I);
  
    /// Module-level debug info verification...
    void verifyCompileUnits();
  
    /// Module-level verification that all @llvm.experimental.deoptimize
    /// declarations share the same calling convention.
    void verifyDeoptimizeCallingConvs();
  
    /// Verify all-or-nothing property of DIFile source attribute within a CU.
    void verifySourceDebugInfo(const DICompileUnit &U, const DIFile &F);
  };
  
  } // end anonymous namespace
  
  /// We know that cond should be true, if not print an error message.
  #define Assert(C, ...) \
    do { if (!(C)) { CheckFailed(__VA_ARGS__); return; } } while (false)
  
  /// We know that a debug info condition should be true, if not print
  /// an error message.
  #define AssertDI(C, ...) \
    do { if (!(C)) { DebugInfoCheckFailed(__VA_ARGS__); return; } } while (false)
  
  void Verifier::visit(Instruction &I) {
    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i)
      Assert(I.getOperand(i) != nullptr, "Operand is null", &I);
    InstVisitor<Verifier>::visit(I);
  }
  
  // Helper to recursively iterate over indirect users. By
  // returning false, the callback can ask to stop recursing
  // further.
  static void forEachUser(const Value *User,
                          SmallPtrSet<const Value *, 32> &Visited,
                          llvm::function_ref<bool(const Value *)> Callback) {
    if (!Visited.insert(User).second)
      return;
    for (const Value *TheNextUser : User->materialized_users())
      if (Callback(TheNextUser))
        forEachUser(TheNextUser, Visited, Callback);
  }
  
  void Verifier::visitGlobalValue(const GlobalValue &GV) {
    Assert(!GV.isDeclaration() || GV.hasValidDeclarationLinkage(),
           "Global is external, but doesn't have external or weak linkage!", &GV);
  
    Assert(GV.getAlignment() <= Value::MaximumAlignment,
           "huge alignment values are unsupported", &GV);
    Assert(!GV.hasAppendingLinkage() || isa<GlobalVariable>(GV),
           "Only global variables can have appending linkage!", &GV);
  
    if (GV.hasAppendingLinkage()) {
      const GlobalVariable *GVar = dyn_cast<GlobalVariable>(&GV);
      Assert(GVar && GVar->getValueType()->isArrayTy(),
             "Only global arrays can have appending linkage!", GVar);
    }
  
    if (GV.isDeclarationForLinker())
      Assert(!GV.hasComdat(), "Declaration may not be in a Comdat!", &GV);
  
    if (GV.hasDLLImportStorageClass()) {
      Assert(!GV.isDSOLocal(),
             "GlobalValue with DLLImport Storage is dso_local!", &GV);
  
      Assert((GV.isDeclaration() && GV.hasExternalLinkage()) ||
                 GV.hasAvailableExternallyLinkage(),
             "Global is marked as dllimport, but not external", &GV);
    }
  
    if (GV.hasLocalLinkage())
      Assert(GV.isDSOLocal(),
             "GlobalValue with private or internal linkage must be dso_local!",
             &GV);
  
    if (!GV.hasDefaultVisibility() && !GV.hasExternalWeakLinkage())
      Assert(GV.isDSOLocal(),
             "GlobalValue with non default visibility must be dso_local!", &GV);
  
    forEachUser(&GV, GlobalValueVisited, [&](const Value *V) -> bool {
      if (const Instruction *I = dyn_cast<Instruction>(V)) {
        if (!I->getParent() || !I->getParent()->getParent())
          CheckFailed("Global is referenced by parentless instruction!", &GV, &M,
                      I);
        else if (I->getParent()->getParent()->getParent() != &M)
          CheckFailed("Global is referenced in a different module!", &GV, &M, I,
                      I->getParent()->getParent(),
                      I->getParent()->getParent()->getParent());
        return false;
      } else if (const Function *F = dyn_cast<Function>(V)) {
        if (F->getParent() != &M)
          CheckFailed("Global is used by function in a different module", &GV, &M,
                      F, F->getParent());
        return false;
      }
      return true;
    });
  }
  
  void Verifier::visitGlobalVariable(const GlobalVariable &GV) {
    if (GV.hasInitializer()) {
      Assert(GV.getInitializer()->getType() == GV.getValueType(),
             "Global variable initializer type does not match global "
             "variable type!",
             &GV);
      // If the global has common linkage, it must have a zero initializer and
      // cannot be constant.
      if (GV.hasCommonLinkage()) {
        Assert(GV.getInitializer()->isNullValue(),
               "'common' global must have a zero initializer!", &GV);
        Assert(!GV.isConstant(), "'common' global may not be marked constant!",
               &GV);
        Assert(!GV.hasComdat(), "'common' global may not be in a Comdat!", &GV);
      }
    }
  
    if (GV.hasName() && (GV.getName() == "llvm.global_ctors" ||
                         GV.getName() == "llvm.global_dtors")) {
      Assert(!GV.hasInitializer() || GV.hasAppendingLinkage(),
             "invalid linkage for intrinsic global variable", &GV);
      // Don't worry about emitting an error for it not being an array,
      // visitGlobalValue will complain on appending non-array.
      if (ArrayType *ATy = dyn_cast<ArrayType>(GV.getValueType())) {
        StructType *STy = dyn_cast<StructType>(ATy->getElementType());
        PointerType *FuncPtrTy =
            FunctionType::get(Type::getVoidTy(Context), false)->
            getPointerTo(DL.getProgramAddressSpace());
        Assert(STy &&
                   (STy->getNumElements() == 2 || STy->getNumElements() == 3) &&
                   STy->getTypeAtIndex(0u)->isIntegerTy(32) &&
                   STy->getTypeAtIndex(1) == FuncPtrTy,
               "wrong type for intrinsic global variable", &GV);
        Assert(STy->getNumElements() == 3,
               "the third field of the element type is mandatory, "
               "specify i8* null to migrate from the obsoleted 2-field form");
        Type *ETy = STy->getTypeAtIndex(2);
        Assert(ETy->isPointerTy() &&
                   cast<PointerType>(ETy)->getElementType()->isIntegerTy(8),
               "wrong type for intrinsic global variable", &GV);
      }
    }
  
    if (GV.hasName() && (GV.getName() == "llvm.used" ||
                         GV.getName() == "llvm.compiler.used")) {
      Assert(!GV.hasInitializer() || GV.hasAppendingLinkage(),
             "invalid linkage for intrinsic global variable", &GV);
      Type *GVType = GV.getValueType();
      if (ArrayType *ATy = dyn_cast<ArrayType>(GVType)) {
        PointerType *PTy = dyn_cast<PointerType>(ATy->getElementType());
        Assert(PTy, "wrong type for intrinsic global variable", &GV);
        if (GV.hasInitializer()) {
          const Constant *Init = GV.getInitializer();
          const ConstantArray *InitArray = dyn_cast<ConstantArray>(Init);
          Assert(InitArray, "wrong initalizer for intrinsic global variable",
                 Init);
          for (Value *Op : InitArray->operands()) {
            Value *V = Op->stripPointerCastsNoFollowAliases();
            Assert(isa<GlobalVariable>(V) || isa<Function>(V) ||
                       isa<GlobalAlias>(V),
                   "invalid llvm.used member", V);
            Assert(V->hasName(), "members of llvm.used must be named", V);
          }
        }
      }
    }
  
    // Visit any debug info attachments.
    SmallVector<MDNode *, 1> MDs;
    GV.getMetadata(LLVMContext::MD_dbg, MDs);
    for (auto *MD : MDs) {
      if (auto *GVE = dyn_cast<DIGlobalVariableExpression>(MD))
        visitDIGlobalVariableExpression(*GVE);
      else
        AssertDI(false, "!dbg attachment of global variable must be a "
                        "DIGlobalVariableExpression");
    }
  
    // Scalable vectors cannot be global variables, since we don't know
    // the runtime size. If the global is a struct or an array containing
    // scalable vectors, that will be caught by the isValidElementType methods
    // in StructType or ArrayType instead.
    if (auto *VTy = dyn_cast<VectorType>(GV.getValueType()))
      Assert(!VTy->isScalable(), "Globals cannot contain scalable vectors", &GV);
  
    if (!GV.hasInitializer()) {
      visitGlobalValue(GV);
      return;
    }
  
    // Walk any aggregate initializers looking for bitcasts between address spaces
    visitConstantExprsRecursively(GV.getInitializer());
  
    visitGlobalValue(GV);
  }
  
  void Verifier::visitAliaseeSubExpr(const GlobalAlias &GA, const Constant &C) {
    SmallPtrSet<const GlobalAlias*, 4> Visited;
    Visited.insert(&GA);
    visitAliaseeSubExpr(Visited, GA, C);
  }
  
  void Verifier::visitAliaseeSubExpr(SmallPtrSetImpl<const GlobalAlias*> &Visited,
                                     const GlobalAlias &GA, const Constant &C) {
    if (const auto *GV = dyn_cast<GlobalValue>(&C)) {
      Assert(!GV->isDeclarationForLinker(), "Alias must point to a definition",
             &GA);
  
      if (const auto *GA2 = dyn_cast<GlobalAlias>(GV)) {
        Assert(Visited.insert(GA2).second, "Aliases cannot form a cycle", &GA);
  
        Assert(!GA2->isInterposable(), "Alias cannot point to an interposable alias",
               &GA);
      } else {
        // Only continue verifying subexpressions of GlobalAliases.
        // Do not recurse into global initializers.
        return;
      }
    }
  
    if (const auto *CE = dyn_cast<ConstantExpr>(&C))
      visitConstantExprsRecursively(CE);
  
    for (const Use &U : C.operands()) {
      Value *V = &*U;
      if (const auto *GA2 = dyn_cast<GlobalAlias>(V))
        visitAliaseeSubExpr(Visited, GA, *GA2->getAliasee());
      else if (const auto *C2 = dyn_cast<Constant>(V))
        visitAliaseeSubExpr(Visited, GA, *C2);
    }
  }
  
  void Verifier::visitGlobalAlias(const GlobalAlias &GA) {
    Assert(GlobalAlias::isValidLinkage(GA.getLinkage()),
           "Alias should have private, internal, linkonce, weak, linkonce_odr, "
           "weak_odr, or external linkage!",
           &GA);
    const Constant *Aliasee = GA.getAliasee();
    Assert(Aliasee, "Aliasee cannot be NULL!", &GA);
    Assert(GA.getType() == Aliasee->getType(),
           "Alias and aliasee types should match!", &GA);
  
    Assert(isa<GlobalValue>(Aliasee) || isa<ConstantExpr>(Aliasee),
           "Aliasee should be either GlobalValue or ConstantExpr", &GA);
  
    visitAliaseeSubExpr(GA, *Aliasee);
  
    visitGlobalValue(GA);
  }
  
  void Verifier::visitNamedMDNode(const NamedMDNode &NMD) {
    // There used to be various other llvm.dbg.* nodes, but we don't support
    // upgrading them and we want to reserve the namespace for future uses.
    if (NMD.getName().startswith("llvm.dbg."))
      AssertDI(NMD.getName() == "llvm.dbg.cu",
               "unrecognized named metadata node in the llvm.dbg namespace",
               &NMD);
    for (const MDNode *MD : NMD.operands()) {
      if (NMD.getName() == "llvm.dbg.cu")
        AssertDI(MD && isa<DICompileUnit>(MD), "invalid compile unit", &NMD, MD);
  
      if (!MD)
        continue;
  
      visitMDNode(*MD);
    }
  }
  
  void Verifier::visitMDNode(const MDNode &MD) {
    // Only visit each node once.  Metadata can be mutually recursive, so this
    // avoids infinite recursion here, as well as being an optimization.
    if (!MDNodes.insert(&MD).second)
      return;
  
    switch (MD.getMetadataID()) {
    default:
      llvm_unreachable("Invalid MDNode subclass");
    case Metadata::MDTupleKind:
      break;
  #define HANDLE_SPECIALIZED_MDNODE_LEAF(CLASS)                                  \
    case Metadata::CLASS##Kind:                                                  \
      visit##CLASS(cast<CLASS>(MD));                                             \
      break;
  #include "llvm/IR/Metadata.def"
    }
  
    for (const Metadata *Op : MD.operands()) {
      if (!Op)
        continue;
      Assert(!isa<LocalAsMetadata>(Op), "Invalid operand for global metadata!",
             &MD, Op);
      if (auto *N = dyn_cast<MDNode>(Op)) {
        visitMDNode(*N);
        continue;
      }
      if (auto *V = dyn_cast<ValueAsMetadata>(Op)) {
        visitValueAsMetadata(*V, nullptr);
        continue;
      }
    }
  
    // Check these last, so we diagnose problems in operands first.
    Assert(!MD.isTemporary(), "Expected no forward declarations!", &MD);
    Assert(MD.isResolved(), "All nodes should be resolved!", &MD);
  }
  
  void Verifier::visitValueAsMetadata(const ValueAsMetadata &MD, Function *F) {
    Assert(MD.getValue(), "Expected valid value", &MD);
    Assert(!MD.getValue()->getType()->isMetadataTy(),
           "Unexpected metadata round-trip through values", &MD, MD.getValue());
  
    auto *L = dyn_cast<LocalAsMetadata>(&MD);
    if (!L)
      return;
  
    Assert(F, "function-local metadata used outside a function", L);
  
    // If this was an instruction, bb, or argument, verify that it is in the
    // function that we expect.
    Function *ActualF = nullptr;
    if (Instruction *I = dyn_cast<Instruction>(L->getValue())) {
      Assert(I->getParent(), "function-local metadata not in basic block", L, I);
      ActualF = I->getParent()->getParent();
    } else if (BasicBlock *BB = dyn_cast<BasicBlock>(L->getValue()))
      ActualF = BB->getParent();
    else if (Argument *A = dyn_cast<Argument>(L->getValue()))
      ActualF = A->getParent();
    assert(ActualF && "Unimplemented function local metadata case!");
  
    Assert(ActualF == F, "function-local metadata used in wrong function", L);
  }
  
  void Verifier::visitMetadataAsValue(const MetadataAsValue &MDV, Function *F) {
    Metadata *MD = MDV.getMetadata();
    if (auto *N = dyn_cast<MDNode>(MD)) {
      visitMDNode(*N);
      return;
    }
  
    // Only visit each node once.  Metadata can be mutually recursive, so this
    // avoids infinite recursion here, as well as being an optimization.
    if (!MDNodes.insert(MD).second)
      return;
  
    if (auto *V = dyn_cast<ValueAsMetadata>(MD))
      visitValueAsMetadata(*V, F);
  }
  
  static bool isType(const Metadata *MD) { return !MD || isa<DIType>(MD); }
  static bool isScope(const Metadata *MD) { return !MD || isa<DIScope>(MD); }
  static bool isDINode(const Metadata *MD) { return !MD || isa<DINode>(MD); }
  
  void Verifier::visitDILocation(const DILocation &N) {
    AssertDI(N.getRawScope() && isa<DILocalScope>(N.getRawScope()),
             "location requires a valid scope", &N, N.getRawScope());
    if (auto *IA = N.getRawInlinedAt())
      AssertDI(isa<DILocation>(IA), "inlined-at should be a location", &N, IA);
    if (auto *SP = dyn_cast<DISubprogram>(N.getRawScope()))
      AssertDI(SP->isDefinition(), "scope points into the type hierarchy", &N);
  }
  
  void Verifier::visitGenericDINode(const GenericDINode &N) {
    AssertDI(N.getTag(), "invalid tag", &N);
  }
  
  void Verifier::visitDIScope(const DIScope &N) {
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
  }
  
  void Verifier::visitDISubrange(const DISubrange &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_subrange_type, "invalid tag", &N);
    auto Count = N.getCount();
    AssertDI(Count, "Count must either be a signed constant or a DIVariable",
             &N);
    AssertDI(!Count.is<ConstantInt*>() ||
                 Count.get<ConstantInt*>()->getSExtValue() >= -1,
             "invalid subrange count", &N);
  }
  
  void Verifier::visitDIEnumerator(const DIEnumerator &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_enumerator, "invalid tag", &N);
  }
  
  void Verifier::visitDIBasicType(const DIBasicType &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_base_type ||
                 N.getTag() == dwarf::DW_TAG_unspecified_type,
             "invalid tag", &N);
    AssertDI(!(N.isBigEndian() && N.isLittleEndian()) ,
              "has conflicting flags", &N);
  }
  
  void Verifier::visitDIDerivedType(const DIDerivedType &N) {
    // Common scope checks.
    visitDIScope(N);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_typedef ||
                 N.getTag() == dwarf::DW_TAG_pointer_type ||
                 N.getTag() == dwarf::DW_TAG_ptr_to_member_type ||
                 N.getTag() == dwarf::DW_TAG_reference_type ||
                 N.getTag() == dwarf::DW_TAG_rvalue_reference_type ||
                 N.getTag() == dwarf::DW_TAG_const_type ||
                 N.getTag() == dwarf::DW_TAG_volatile_type ||
                 N.getTag() == dwarf::DW_TAG_restrict_type ||
                 N.getTag() == dwarf::DW_TAG_atomic_type ||
                 N.getTag() == dwarf::DW_TAG_member ||
                 N.getTag() == dwarf::DW_TAG_inheritance ||
                 N.getTag() == dwarf::DW_TAG_friend,
             "invalid tag", &N);
    if (N.getTag() == dwarf::DW_TAG_ptr_to_member_type) {
      AssertDI(isType(N.getRawExtraData()), "invalid pointer to member type", &N,
               N.getRawExtraData());
    }
  
    AssertDI(isScope(N.getRawScope()), "invalid scope", &N, N.getRawScope());
    AssertDI(isType(N.getRawBaseType()), "invalid base type", &N,
             N.getRawBaseType());
  
    if (N.getDWARFAddressSpace()) {
      AssertDI(N.getTag() == dwarf::DW_TAG_pointer_type ||
                   N.getTag() == dwarf::DW_TAG_reference_type ||
                   N.getTag() == dwarf::DW_TAG_rvalue_reference_type,
               "DWARF address space only applies to pointer or reference types",
               &N);
    }
  }
  
  /// Detect mutually exclusive flags.
  static bool hasConflictingReferenceFlags(unsigned Flags) {
    return ((Flags & DINode::FlagLValueReference) &&
            (Flags & DINode::FlagRValueReference)) ||
           ((Flags & DINode::FlagTypePassByValue) &&
            (Flags & DINode::FlagTypePassByReference));
  }
  
  void Verifier::visitTemplateParams(const MDNode &N, const Metadata &RawParams) {
    auto *Params = dyn_cast<MDTuple>(&RawParams);
    AssertDI(Params, "invalid template params", &N, &RawParams);
    for (Metadata *Op : Params->operands()) {
      AssertDI(Op && isa<DITemplateParameter>(Op), "invalid template parameter",
               &N, Params, Op);
    }
  }
  
  void Verifier::visitDICompositeType(const DICompositeType &N) {
    // Common scope checks.
    visitDIScope(N);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_array_type ||
                 N.getTag() == dwarf::DW_TAG_structure_type ||
                 N.getTag() == dwarf::DW_TAG_union_type ||
                 N.getTag() == dwarf::DW_TAG_enumeration_type ||
                 N.getTag() == dwarf::DW_TAG_class_type ||
                 N.getTag() == dwarf::DW_TAG_variant_part,
             "invalid tag", &N);
  
    AssertDI(isScope(N.getRawScope()), "invalid scope", &N, N.getRawScope());
    AssertDI(isType(N.getRawBaseType()), "invalid base type", &N,
             N.getRawBaseType());
  
    AssertDI(!N.getRawElements() || isa<MDTuple>(N.getRawElements()),
             "invalid composite elements", &N, N.getRawElements());
    AssertDI(isType(N.getRawVTableHolder()), "invalid vtable holder", &N,
             N.getRawVTableHolder());
    AssertDI(!hasConflictingReferenceFlags(N.getFlags()),
             "invalid reference flags", &N);
  
    if (N.isVector()) {
      const DINodeArray Elements = N.getElements();
      AssertDI(Elements.size() == 1 &&
               Elements[0]->getTag() == dwarf::DW_TAG_subrange_type,
               "invalid vector, expected one element of type subrange", &N);
    }
  
    if (auto *Params = N.getRawTemplateParams())
      visitTemplateParams(N, *Params);
  
    if (N.getTag() == dwarf::DW_TAG_class_type ||
        N.getTag() == dwarf::DW_TAG_union_type) {
      AssertDI(N.getFile() && !N.getFile()->getFilename().empty(),
               "class/union requires a filename", &N, N.getFile());
    }
  
    if (auto *D = N.getRawDiscriminator()) {
      AssertDI(isa<DIDerivedType>(D) && N.getTag() == dwarf::DW_TAG_variant_part,
               "discriminator can only appear on variant part");
    }
  }
  
  void Verifier::visitDISubroutineType(const DISubroutineType &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_subroutine_type, "invalid tag", &N);
    if (auto *Types = N.getRawTypeArray()) {
      AssertDI(isa<MDTuple>(Types), "invalid composite elements", &N, Types);
      for (Metadata *Ty : N.getTypeArray()->operands()) {
        AssertDI(isType(Ty), "invalid subroutine type ref", &N, Types, Ty);
      }
    }
    AssertDI(!hasConflictingReferenceFlags(N.getFlags()),
             "invalid reference flags", &N);
  }
  
  void Verifier::visitDIFile(const DIFile &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_file_type, "invalid tag", &N);
    Optional<DIFile::ChecksumInfo<StringRef>> Checksum = N.getChecksum();
    if (Checksum) {
      AssertDI(Checksum->Kind <= DIFile::ChecksumKind::CSK_Last,
               "invalid checksum kind", &N);
      size_t Size;
      switch (Checksum->Kind) {
      case DIFile::CSK_MD5:
        Size = 32;
        break;
      case DIFile::CSK_SHA1:
        Size = 40;
        break;
      }
      AssertDI(Checksum->Value.size() == Size, "invalid checksum length", &N);
      AssertDI(Checksum->Value.find_if_not(llvm::isHexDigit) == StringRef::npos,
               "invalid checksum", &N);
    }
  }
  
  void Verifier::visitDICompileUnit(const DICompileUnit &N) {
    AssertDI(N.isDistinct(), "compile units must be distinct", &N);
    AssertDI(N.getTag() == dwarf::DW_TAG_compile_unit, "invalid tag", &N);
  
    // Don't bother verifying the compilation directory or producer string
    // as those could be empty.
    AssertDI(N.getRawFile() && isa<DIFile>(N.getRawFile()), "invalid file", &N,
             N.getRawFile());
    AssertDI(!N.getFile()->getFilename().empty(), "invalid filename", &N,
             N.getFile());
  
    verifySourceDebugInfo(N, *N.getFile());
  
    AssertDI((N.getEmissionKind() <= DICompileUnit::LastEmissionKind),
             "invalid emission kind", &N);
  
    if (auto *Array = N.getRawEnumTypes()) {
      AssertDI(isa<MDTuple>(Array), "invalid enum list", &N, Array);
      for (Metadata *Op : N.getEnumTypes()->operands()) {
        auto *Enum = dyn_cast_or_null<DICompositeType>(Op);
        AssertDI(Enum && Enum->getTag() == dwarf::DW_TAG_enumeration_type,
                 "invalid enum type", &N, N.getEnumTypes(), Op);
      }
    }
    if (auto *Array = N.getRawRetainedTypes()) {
      AssertDI(isa<MDTuple>(Array), "invalid retained type list", &N, Array);
      for (Metadata *Op : N.getRetainedTypes()->operands()) {
        AssertDI(Op && (isa<DIType>(Op) ||
                        (isa<DISubprogram>(Op) &&
                         !cast<DISubprogram>(Op)->isDefinition())),
                 "invalid retained type", &N, Op);
      }
    }
    if (auto *Array = N.getRawGlobalVariables()) {
      AssertDI(isa<MDTuple>(Array), "invalid global variable list", &N, Array);
      for (Metadata *Op : N.getGlobalVariables()->operands()) {
        AssertDI(Op && (isa<DIGlobalVariableExpression>(Op)),
                 "invalid global variable ref", &N, Op);
      }
    }
    if (auto *Array = N.getRawImportedEntities()) {
      AssertDI(isa<MDTuple>(Array), "invalid imported entity list", &N, Array);
      for (Metadata *Op : N.getImportedEntities()->operands()) {
        AssertDI(Op && isa<DIImportedEntity>(Op), "invalid imported entity ref",
                 &N, Op);
      }
    }
    if (auto *Array = N.getRawMacros()) {
      AssertDI(isa<MDTuple>(Array), "invalid macro list", &N, Array);
      for (Metadata *Op : N.getMacros()->operands()) {
        AssertDI(Op && isa<DIMacroNode>(Op), "invalid macro ref", &N, Op);
      }
    }
    CUVisited.insert(&N);
  }
  
  void Verifier::visitDISubprogram(const DISubprogram &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_subprogram, "invalid tag", &N);
    AssertDI(isScope(N.getRawScope()), "invalid scope", &N, N.getRawScope());
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
    else
      AssertDI(N.getLine() == 0, "line specified with no file", &N, N.getLine());
    if (auto *T = N.getRawType())
      AssertDI(isa<DISubroutineType>(T), "invalid subroutine type", &N, T);
    AssertDI(isType(N.getRawContainingType()), "invalid containing type", &N,
             N.getRawContainingType());
    if (auto *Params = N.getRawTemplateParams())
      visitTemplateParams(N, *Params);
    if (auto *S = N.getRawDeclaration())
      AssertDI(isa<DISubprogram>(S) && !cast<DISubprogram>(S)->isDefinition(),
               "invalid subprogram declaration", &N, S);
    if (auto *RawNode = N.getRawRetainedNodes()) {
      auto *Node = dyn_cast<MDTuple>(RawNode);
      AssertDI(Node, "invalid retained nodes list", &N, RawNode);
      for (Metadata *Op : Node->operands()) {
        AssertDI(Op && (isa<DILocalVariable>(Op) || isa<DILabel>(Op)),
                 "invalid retained nodes, expected DILocalVariable or DILabel",
                 &N, Node, Op);
      }
    }
    AssertDI(!hasConflictingReferenceFlags(N.getFlags()),
             "invalid reference flags", &N);
  
    auto *Unit = N.getRawUnit();
    if (N.isDefinition()) {
      // Subprogram definitions (not part of the type hierarchy).
      AssertDI(N.isDistinct(), "subprogram definitions must be distinct", &N);
      AssertDI(Unit, "subprogram definitions must have a compile unit", &N);
      AssertDI(isa<DICompileUnit>(Unit), "invalid unit type", &N, Unit);
      if (N.getFile())
        verifySourceDebugInfo(*N.getUnit(), *N.getFile());
    } else {
      // Subprogram declarations (part of the type hierarchy).
      AssertDI(!Unit, "subprogram declarations must not have a compile unit", &N);
    }
  
    if (auto *RawThrownTypes = N.getRawThrownTypes()) {
      auto *ThrownTypes = dyn_cast<MDTuple>(RawThrownTypes);
      AssertDI(ThrownTypes, "invalid thrown types list", &N, RawThrownTypes);
      for (Metadata *Op : ThrownTypes->operands())
        AssertDI(Op && isa<DIType>(Op), "invalid thrown type", &N, ThrownTypes,
                 Op);
    }
  
    if (N.areAllCallsDescribed())
      AssertDI(N.isDefinition(),
               "DIFlagAllCallsDescribed must be attached to a definition");
  }
  
  void Verifier::visitDILexicalBlockBase(const DILexicalBlockBase &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_lexical_block, "invalid tag", &N);
    AssertDI(N.getRawScope() && isa<DILocalScope>(N.getRawScope()),
             "invalid local scope", &N, N.getRawScope());
    if (auto *SP = dyn_cast<DISubprogram>(N.getRawScope()))
      AssertDI(SP->isDefinition(), "scope points into the type hierarchy", &N);
  }
  
  void Verifier::visitDILexicalBlock(const DILexicalBlock &N) {
    visitDILexicalBlockBase(N);
  
    AssertDI(N.getLine() || !N.getColumn(),
             "cannot have column info without line info", &N);
  }
  
  void Verifier::visitDILexicalBlockFile(const DILexicalBlockFile &N) {
    visitDILexicalBlockBase(N);
  }
  
  void Verifier::visitDICommonBlock(const DICommonBlock &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_common_block, "invalid tag", &N);
    if (auto *S = N.getRawScope())
      AssertDI(isa<DIScope>(S), "invalid scope ref", &N, S);
    if (auto *S = N.getRawDecl())
      AssertDI(isa<DIGlobalVariable>(S), "invalid declaration", &N, S);
  }
  
  void Verifier::visitDINamespace(const DINamespace &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_namespace, "invalid tag", &N);
    if (auto *S = N.getRawScope())
      AssertDI(isa<DIScope>(S), "invalid scope ref", &N, S);
  }
  
  void Verifier::visitDIMacro(const DIMacro &N) {
    AssertDI(N.getMacinfoType() == dwarf::DW_MACINFO_define ||
                 N.getMacinfoType() == dwarf::DW_MACINFO_undef,
             "invalid macinfo type", &N);
    AssertDI(!N.getName().empty(), "anonymous macro", &N);
    if (!N.getValue().empty()) {
      assert(N.getValue().data()[0] != ' ' && "Macro value has a space prefix");
    }
  }
  
  void Verifier::visitDIMacroFile(const DIMacroFile &N) {
    AssertDI(N.getMacinfoType() == dwarf::DW_MACINFO_start_file,
             "invalid macinfo type", &N);
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
  
    if (auto *Array = N.getRawElements()) {
      AssertDI(isa<MDTuple>(Array), "invalid macro list", &N, Array);
      for (Metadata *Op : N.getElements()->operands()) {
        AssertDI(Op && isa<DIMacroNode>(Op), "invalid macro ref", &N, Op);
      }
    }
  }
  
  void Verifier::visitDIModule(const DIModule &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_module, "invalid tag", &N);
    AssertDI(!N.getName().empty(), "anonymous module", &N);
  }
  
  void Verifier::visitDITemplateParameter(const DITemplateParameter &N) {
    AssertDI(isType(N.getRawType()), "invalid type ref", &N, N.getRawType());
  }
  
  void Verifier::visitDITemplateTypeParameter(const DITemplateTypeParameter &N) {
    visitDITemplateParameter(N);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_template_type_parameter, "invalid tag",
             &N);
  }
  
  void Verifier::visitDITemplateValueParameter(
      const DITemplateValueParameter &N) {
    visitDITemplateParameter(N);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_template_value_parameter ||
                 N.getTag() == dwarf::DW_TAG_GNU_template_template_param ||
                 N.getTag() == dwarf::DW_TAG_GNU_template_parameter_pack,
             "invalid tag", &N);
  }
  
  void Verifier::visitDIVariable(const DIVariable &N) {
    if (auto *S = N.getRawScope())
      AssertDI(isa<DIScope>(S), "invalid scope", &N, S);
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
  }
  
  void Verifier::visitDIGlobalVariable(const DIGlobalVariable &N) {
    // Checks common to all variables.
    visitDIVariable(N);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_variable, "invalid tag", &N);
    AssertDI(isType(N.getRawType()), "invalid type ref", &N, N.getRawType());
    AssertDI(N.getType(), "missing global variable type", &N);
    if (auto *Member = N.getRawStaticDataMemberDeclaration()) {
      AssertDI(isa<DIDerivedType>(Member),
               "invalid static data member declaration", &N, Member);
    }
  }
  
  void Verifier::visitDILocalVariable(const DILocalVariable &N) {
    // Checks common to all variables.
    visitDIVariable(N);
  
    AssertDI(isType(N.getRawType()), "invalid type ref", &N, N.getRawType());
    AssertDI(N.getTag() == dwarf::DW_TAG_variable, "invalid tag", &N);
    AssertDI(N.getRawScope() && isa<DILocalScope>(N.getRawScope()),
             "local variable requires a valid scope", &N, N.getRawScope());
    if (auto Ty = N.getType())
      AssertDI(!isa<DISubroutineType>(Ty), "invalid type", &N, N.getType());
  }
  
  void Verifier::visitDILabel(const DILabel &N) {
    if (auto *S = N.getRawScope())
      AssertDI(isa<DIScope>(S), "invalid scope", &N, S);
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
  
    AssertDI(N.getTag() == dwarf::DW_TAG_label, "invalid tag", &N);
    AssertDI(N.getRawScope() && isa<DILocalScope>(N.getRawScope()),
             "label requires a valid scope", &N, N.getRawScope());
  }
  
  void Verifier::visitDIExpression(const DIExpression &N) {
    AssertDI(N.isValid(), "invalid expression", &N);
  }
  
  void Verifier::visitDIGlobalVariableExpression(
      const DIGlobalVariableExpression &GVE) {
    AssertDI(GVE.getVariable(), "missing variable");
    if (auto *Var = GVE.getVariable())
      visitDIGlobalVariable(*Var);
    if (auto *Expr = GVE.getExpression()) {
      visitDIExpression(*Expr);
      if (auto Fragment = Expr->getFragmentInfo())
        verifyFragmentExpression(*GVE.getVariable(), *Fragment, &GVE);
    }
  }
  
  void Verifier::visitDIObjCProperty(const DIObjCProperty &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_APPLE_property, "invalid tag", &N);
    if (auto *T = N.getRawType())
      AssertDI(isType(T), "invalid type ref", &N, T);
    if (auto *F = N.getRawFile())
      AssertDI(isa<DIFile>(F), "invalid file", &N, F);
  }
  
  void Verifier::visitDIImportedEntity(const DIImportedEntity &N) {
    AssertDI(N.getTag() == dwarf::DW_TAG_imported_module ||
                 N.getTag() == dwarf::DW_TAG_imported_declaration,
             "invalid tag", &N);
    if (auto *S = N.getRawScope())
      AssertDI(isa<DIScope>(S), "invalid scope for imported entity", &N, S);
    AssertDI(isDINode(N.getRawEntity()), "invalid imported entity", &N,
             N.getRawEntity());
  }
  
  void Verifier::visitComdat(const Comdat &C) {
    // The Module is invalid if the GlobalValue has private linkage.  Entities
    // with private linkage don't have entries in the symbol table.
    if (const GlobalValue *GV = M.getNamedValue(C.getName()))
      Assert(!GV->hasPrivateLinkage(), "comdat global value has private linkage",
             GV);
  }
  
  void Verifier::visitModuleIdents(const Module &M) {
    const NamedMDNode *Idents = M.getNamedMetadata("llvm.ident");
    if (!Idents)
      return;
  
    // llvm.ident takes a list of metadata entry. Each entry has only one string.
    // Scan each llvm.ident entry and make sure that this requirement is met.
    for (const MDNode *N : Idents->operands()) {
      Assert(N->getNumOperands() == 1,
             "incorrect number of operands in llvm.ident metadata", N);
      Assert(dyn_cast_or_null<MDString>(N->getOperand(0)),
             ("invalid value for llvm.ident metadata entry operand"
              "(the operand should be a string)"),
             N->getOperand(0));
    }
  }
  
  void Verifier::visitModuleCommandLines(const Module &M) {
    const NamedMDNode *CommandLines = M.getNamedMetadata("llvm.commandline");
    if (!CommandLines)
      return;
  
    // llvm.commandline takes a list of metadata entry. Each entry has only one
    // string. Scan each llvm.commandline entry and make sure that this
    // requirement is met.
    for (const MDNode *N : CommandLines->operands()) {
      Assert(N->getNumOperands() == 1,
             "incorrect number of operands in llvm.commandline metadata", N);
      Assert(dyn_cast_or_null<MDString>(N->getOperand(0)),
             ("invalid value for llvm.commandline metadata entry operand"
              "(the operand should be a string)"),
             N->getOperand(0));
    }
  }
  
  void Verifier::visitModuleFlags(const Module &M) {
    const NamedMDNode *Flags = M.getModuleFlagsMetadata();
    if (!Flags) return;
  
    // Scan each flag, and track the flags and requirements.
    DenseMap<const MDString*, const MDNode*> SeenIDs;
    SmallVector<const MDNode*, 16> Requirements;
    for (const MDNode *MDN : Flags->operands())
      visitModuleFlag(MDN, SeenIDs, Requirements);
  
    // Validate that the requirements in the module are valid.
    for (const MDNode *Requirement : Requirements) {
      const MDString *Flag = cast<MDString>(Requirement->getOperand(0));
      const Metadata *ReqValue = Requirement->getOperand(1);
  
      const MDNode *Op = SeenIDs.lookup(Flag);
      if (!Op) {
        CheckFailed("invalid requirement on flag, flag is not present in module",
                    Flag);
        continue;
      }
  
      if (Op->getOperand(2) != ReqValue) {
        CheckFailed(("invalid requirement on flag, "
                     "flag does not have the required value"),
                    Flag);
        continue;
      }
    }
  }
  
  void
  Verifier::visitModuleFlag(const MDNode *Op,
                            DenseMap<const MDString *, const MDNode *> &SeenIDs,
                            SmallVectorImpl<const MDNode *> &Requirements) {
    // Each module flag should have three arguments, the merge behavior (a
    // constant int), the flag ID (an MDString), and the value.
    Assert(Op->getNumOperands() == 3,
           "incorrect number of operands in module flag", Op);
    Module::ModFlagBehavior MFB;
    if (!Module::isValidModFlagBehavior(Op->getOperand(0), MFB)) {
      Assert(
          mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(0)),
          "invalid behavior operand in module flag (expected constant integer)",
          Op->getOperand(0));
      Assert(false,
             "invalid behavior operand in module flag (unexpected constant)",
             Op->getOperand(0));
    }
    MDString *ID = dyn_cast_or_null<MDString>(Op->getOperand(1));
    Assert(ID, "invalid ID operand in module flag (expected metadata string)",
           Op->getOperand(1));
  
    // Sanity check the values for behaviors with additional requirements.
    switch (MFB) {
    case Module::Error:
    case Module::Warning:
    case Module::Override:
      // These behavior types accept any value.
      break;
  
    case Module::Max: {
      Assert(mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(2)),
             "invalid value for 'max' module flag (expected constant integer)",
             Op->getOperand(2));
      break;
    }
  
    case Module::Require: {
      // The value should itself be an MDNode with two operands, a flag ID (an
      // MDString), and a value.
      MDNode *Value = dyn_cast<MDNode>(Op->getOperand(2));
      Assert(Value && Value->getNumOperands() == 2,
             "invalid value for 'require' module flag (expected metadata pair)",
             Op->getOperand(2));
      Assert(isa<MDString>(Value->getOperand(0)),
             ("invalid value for 'require' module flag "
              "(first value operand should be a string)"),
             Value->getOperand(0));
  
      // Append it to the list of requirements, to check once all module flags are
      // scanned.
      Requirements.push_back(Value);
      break;
    }
  
    case Module::Append:
    case Module::AppendUnique: {
      // These behavior types require the operand be an MDNode.
      Assert(isa<MDNode>(Op->getOperand(2)),
             "invalid value for 'append'-type module flag "
             "(expected a metadata node)",
             Op->getOperand(2));
      break;
    }
    }
  
    // Unless this is a "requires" flag, check the ID is unique.
    if (MFB != Module::Require) {
      bool Inserted = SeenIDs.insert(std::make_pair(ID, Op)).second;
      Assert(Inserted,
             "module flag identifiers must be unique (or of 'require' type)", ID);
    }
  
    if (ID->getString() == "wchar_size") {
      ConstantInt *Value
        = mdconst::dyn_extract_or_null<ConstantInt>(Op->getOperand(2));
      Assert(Value, "wchar_size metadata requires constant integer argument");
    }
  
    if (ID->getString() == "Linker Options") {
      // If the llvm.linker.options named metadata exists, we assume that the
      // bitcode reader has upgraded the module flag. Otherwise the flag might
      // have been created by a client directly.
      Assert(M.getNamedMetadata("llvm.linker.options"),
             "'Linker Options' named metadata no longer supported");
    }
  
    if (ID->getString() == "CG Profile") {
      for (const MDOperand &MDO : cast<MDNode>(Op->getOperand(2))->operands())
        visitModuleFlagCGProfileEntry(MDO);
    }
  }
  
  void Verifier::visitModuleFlagCGProfileEntry(const MDOperand &MDO) {
    auto CheckFunction = [&](const MDOperand &FuncMDO) {
      if (!FuncMDO)
        return;
      auto F = dyn_cast<ValueAsMetadata>(FuncMDO);
      Assert(F && isa<Function>(F->getValue()), "expected a Function or null",
             FuncMDO);
    };
    auto Node = dyn_cast_or_null<MDNode>(MDO);
    Assert(Node && Node->getNumOperands() == 3, "expected a MDNode triple", MDO);
    CheckFunction(Node->getOperand(0));
    CheckFunction(Node->getOperand(1));
    auto Count = dyn_cast_or_null<ConstantAsMetadata>(Node->getOperand(2));
    Assert(Count && Count->getType()->isIntegerTy(),
           "expected an integer constant", Node->getOperand(2));
  }
  
  /// Return true if this attribute kind only applies to functions.
  static bool isFuncOnlyAttr(Attribute::AttrKind Kind) {
    switch (Kind) {
    case Attribute::NoReturn:
    case Attribute::NoSync:
    case Attribute::WillReturn:
    case Attribute::NoCfCheck:
    case Attribute::NoUnwind:
    case Attribute::NoInline:
    case Attribute::NoFree:
    case Attribute::AlwaysInline:
    case Attribute::OptimizeForSize:
    case Attribute::StackProtect:
    case Attribute::StackProtectReq:
    case Attribute::StackProtectStrong:
    case Attribute::SafeStack:
    case Attribute::ShadowCallStack:
    case Attribute::NoRedZone:
    case Attribute::NoImplicitFloat:
    case Attribute::Naked:
    case Attribute::InlineHint:
    case Attribute::StackAlignment:
    case Attribute::UWTable:
    case Attribute::NonLazyBind:
    case Attribute::ReturnsTwice:
    case Attribute::SanitizeAddress:
    case Attribute::SanitizeHWAddress:
    case Attribute::SanitizeMemTag:
    case Attribute::SanitizeThread:
    case Attribute::SanitizeMemory:
    case Attribute::MinSize:
    case Attribute::NoDuplicate:
    case Attribute::Builtin:
    case Attribute::NoBuiltin:
    case Attribute::Cold:
    case Attribute::OptForFuzzing:
    case Attribute::OptimizeNone:
    case Attribute::JumpTable:
    case Attribute::Convergent:
    case Attribute::ArgMemOnly:
    case Attribute::NoRecurse:
    case Attribute::InaccessibleMemOnly:
    case Attribute::InaccessibleMemOrArgMemOnly:
    case Attribute::AllocSize:
    case Attribute::SpeculativeLoadHardening:
    case Attribute::Speculatable:
    case Attribute::StrictFP:
      return true;
    default:
      break;
    }
    return false;
  }
  
  /// Return true if this is a function attribute that can also appear on
  /// arguments.
  static bool isFuncOrArgAttr(Attribute::AttrKind Kind) {
    return Kind == Attribute::ReadOnly || Kind == Attribute::WriteOnly ||
           Kind == Attribute::ReadNone;
  }
  
  void Verifier::verifyAttributeTypes(AttributeSet Attrs, bool IsFunction,
                                      const Value *V) {
    for (Attribute A : Attrs) {
      if (A.isStringAttribute())
        continue;
  
      if (isFuncOnlyAttr(A.getKindAsEnum())) {
        if (!IsFunction) {
          CheckFailed("Attribute '" + A.getAsString() +
                          "' only applies to functions!",
                      V);
          return;
        }
      } else if (IsFunction && !isFuncOrArgAttr(A.getKindAsEnum())) {
        CheckFailed("Attribute '" + A.getAsString() +
                        "' does not apply to functions!",
                    V);
        return;
      }
    }
  }
  
  // VerifyParameterAttrs - Check the given attributes for an argument or return
  // value of the specified type.  The value V is printed in error messages.
  void Verifier::verifyParameterAttrs(AttributeSet Attrs, Type *Ty,
                                      const Value *V) {
    if (!Attrs.hasAttributes())
      return;
  
    verifyAttributeTypes(Attrs, /*IsFunction=*/false, V);
  
    if (Attrs.hasAttribute(Attribute::ImmArg)) {
      Assert(Attrs.getNumAttributes() == 1,
             "Attribute 'immarg' is incompatible with other attributes", V);
    }
  
    // Check for mutually incompatible attributes.  Only inreg is compatible with
    // sret.
    unsigned AttrCount = 0;
    AttrCount += Attrs.hasAttribute(Attribute::ByVal);
    AttrCount += Attrs.hasAttribute(Attribute::InAlloca);
    AttrCount += Attrs.hasAttribute(Attribute::StructRet) ||
                 Attrs.hasAttribute(Attribute::InReg);
    AttrCount += Attrs.hasAttribute(Attribute::Nest);
    Assert(AttrCount <= 1, "Attributes 'byval', 'inalloca', 'inreg', 'nest', "
                           "and 'sret' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::InAlloca) &&
             Attrs.hasAttribute(Attribute::ReadOnly)),
           "Attributes "
           "'inalloca and readonly' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::StructRet) &&
             Attrs.hasAttribute(Attribute::Returned)),
           "Attributes "
           "'sret and returned' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::ZExt) &&
             Attrs.hasAttribute(Attribute::SExt)),
           "Attributes "
           "'zeroext and signext' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::ReadNone) &&
             Attrs.hasAttribute(Attribute::ReadOnly)),
           "Attributes "
           "'readnone and readonly' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::ReadNone) &&
             Attrs.hasAttribute(Attribute::WriteOnly)),
           "Attributes "
           "'readnone and writeonly' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::ReadOnly) &&
             Attrs.hasAttribute(Attribute::WriteOnly)),
           "Attributes "
           "'readonly and writeonly' are incompatible!",
           V);
  
    Assert(!(Attrs.hasAttribute(Attribute::NoInline) &&
             Attrs.hasAttribute(Attribute::AlwaysInline)),
           "Attributes "
           "'noinline and alwaysinline' are incompatible!",
           V);
  
    if (Attrs.hasAttribute(Attribute::ByVal) && Attrs.getByValType()) {
      Assert(Attrs.getByValType() == cast<PointerType>(Ty)->getElementType(),
             "Attribute 'byval' type does not match parameter!", V);
    }
  
    AttrBuilder IncompatibleAttrs = AttributeFuncs::typeIncompatible(Ty);
    Assert(!AttrBuilder(Attrs).overlaps(IncompatibleAttrs),
           "Wrong types for attribute: " +
               AttributeSet::get(Context, IncompatibleAttrs).getAsString(),
           V);
  
    if (PointerType *PTy = dyn_cast<PointerType>(Ty)) {
      SmallPtrSet<Type*, 4> Visited;
      if (!PTy->getElementType()->isSized(&Visited)) {
        Assert(!Attrs.hasAttribute(Attribute::ByVal) &&
                   !Attrs.hasAttribute(Attribute::InAlloca),
               "Attributes 'byval' and 'inalloca' do not support unsized types!",
               V);
      }
      if (!isa<PointerType>(PTy->getElementType()))
        Assert(!Attrs.hasAttribute(Attribute::SwiftError),
               "Attribute 'swifterror' only applies to parameters "
               "with pointer to pointer type!",
               V);
    } else {
      Assert(!Attrs.hasAttribute(Attribute::ByVal),
             "Attribute 'byval' only applies to parameters with pointer type!",
             V);
      Assert(!Attrs.hasAttribute(Attribute::SwiftError),
             "Attribute 'swifterror' only applies to parameters "
             "with pointer type!",
             V);
    }
  }
  
  // Check parameter attributes against a function type.
  // The value V is printed in error messages.
  void Verifier::verifyFunctionAttrs(FunctionType *FT, AttributeList Attrs,
                                     const Value *V, bool IsIntrinsic) {
    if (Attrs.isEmpty())
      return;
  
    bool SawNest = false;
    bool SawReturned = false;
    bool SawSRet = false;
    bool SawSwiftSelf = false;
    bool SawSwiftError = false;
  
    // Verify return value attributes.
    AttributeSet RetAttrs = Attrs.getRetAttributes();
    Assert((!RetAttrs.hasAttribute(Attribute::ByVal) &&
            !RetAttrs.hasAttribute(Attribute::Nest) &&
            !RetAttrs.hasAttribute(Attribute::StructRet) &&
            !RetAttrs.hasAttribute(Attribute::NoCapture) &&
            !RetAttrs.hasAttribute(Attribute::Returned) &&
            !RetAttrs.hasAttribute(Attribute::InAlloca) &&
            !RetAttrs.hasAttribute(Attribute::SwiftSelf) &&
            !RetAttrs.hasAttribute(Attribute::SwiftError)),
           "Attributes 'byval', 'inalloca', 'nest', 'sret', 'nocapture', "
           "'returned', 'swiftself', and 'swifterror' do not apply to return "
           "values!",
           V);
    Assert((!RetAttrs.hasAttribute(Attribute::ReadOnly) &&
            !RetAttrs.hasAttribute(Attribute::WriteOnly) &&
            !RetAttrs.hasAttribute(Attribute::ReadNone)),
           "Attribute '" + RetAttrs.getAsString() +
               "' does not apply to function returns",
           V);
    verifyParameterAttrs(RetAttrs, FT->getReturnType(), V);
  
    // Verify parameter attributes.
    for (unsigned i = 0, e = FT->getNumParams(); i != e; ++i) {
      Type *Ty = FT->getParamType(i);
      AttributeSet ArgAttrs = Attrs.getParamAttributes(i);
  
      if (!IsIntrinsic) {
        Assert(!ArgAttrs.hasAttribute(Attribute::ImmArg),
               "immarg attribute only applies to intrinsics",V);
      }
  
      verifyParameterAttrs(ArgAttrs, Ty, V);
  
      if (ArgAttrs.hasAttribute(Attribute::Nest)) {
        Assert(!SawNest, "More than one parameter has attribute nest!", V);
        SawNest = true;
      }
  
      if (ArgAttrs.hasAttribute(Attribute::Returned)) {
        Assert(!SawReturned, "More than one parameter has attribute returned!",
               V);
        Assert(Ty->canLosslesslyBitCastTo(FT->getReturnType()),
               "Incompatible argument and return types for 'returned' attribute",
               V);
        SawReturned = true;
      }
  
      if (ArgAttrs.hasAttribute(Attribute::StructRet)) {
        Assert(!SawSRet, "Cannot have multiple 'sret' parameters!", V);
        Assert(i == 0 || i == 1,
               "Attribute 'sret' is not on first or second parameter!", V);
        SawSRet = true;
      }
  
      if (ArgAttrs.hasAttribute(Attribute::SwiftSelf)) {
        Assert(!SawSwiftSelf, "Cannot have multiple 'swiftself' parameters!", V);
        SawSwiftSelf = true;
      }
  
      if (ArgAttrs.hasAttribute(Attribute::SwiftError)) {
        Assert(!SawSwiftError, "Cannot have multiple 'swifterror' parameters!",
               V);
        SawSwiftError = true;
      }
  
      if (ArgAttrs.hasAttribute(Attribute::InAlloca)) {
        Assert(i == FT->getNumParams() - 1,
               "inalloca isn't on the last parameter!", V);
      }
    }
  
    if (!Attrs.hasAttributes(AttributeList::FunctionIndex))
      return;
  
    verifyAttributeTypes(Attrs.getFnAttributes(), /*IsFunction=*/true, V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::ReadNone) &&
             Attrs.hasFnAttribute(Attribute::ReadOnly)),
           "Attributes 'readnone and readonly' are incompatible!", V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::ReadNone) &&
             Attrs.hasFnAttribute(Attribute::WriteOnly)),
           "Attributes 'readnone and writeonly' are incompatible!", V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::ReadOnly) &&
             Attrs.hasFnAttribute(Attribute::WriteOnly)),
           "Attributes 'readonly and writeonly' are incompatible!", V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::ReadNone) &&
             Attrs.hasFnAttribute(Attribute::InaccessibleMemOrArgMemOnly)),
           "Attributes 'readnone and inaccessiblemem_or_argmemonly' are "
           "incompatible!",
           V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::ReadNone) &&
             Attrs.hasFnAttribute(Attribute::InaccessibleMemOnly)),
           "Attributes 'readnone and inaccessiblememonly' are incompatible!", V);
  
    Assert(!(Attrs.hasFnAttribute(Attribute::NoInline) &&
             Attrs.hasFnAttribute(Attribute::AlwaysInline)),
           "Attributes 'noinline and alwaysinline' are incompatible!", V);
  
    if (Attrs.hasFnAttribute(Attribute::OptimizeNone)) {
      Assert(Attrs.hasFnAttribute(Attribute::NoInline),
             "Attribute 'optnone' requires 'noinline'!", V);
  
      Assert(!Attrs.hasFnAttribute(Attribute::OptimizeForSize),
             "Attributes 'optsize and optnone' are incompatible!", V);
  
      Assert(!Attrs.hasFnAttribute(Attribute::MinSize),
             "Attributes 'minsize and optnone' are incompatible!", V);
    }
  
    if (Attrs.hasFnAttribute(Attribute::JumpTable)) {
      const GlobalValue *GV = cast<GlobalValue>(V);
      Assert(GV->hasGlobalUnnamedAddr(),
             "Attribute 'jumptable' requires 'unnamed_addr'", V);
    }
  
    if (Attrs.hasFnAttribute(Attribute::AllocSize)) {
      std::pair<unsigned, Optional<unsigned>> Args =
          Attrs.getAllocSizeArgs(AttributeList::FunctionIndex);
  
      auto CheckParam = [&](StringRef Name, unsigned ParamNo) {
        if (ParamNo >= FT->getNumParams()) {
          CheckFailed("'allocsize' " + Name + " argument is out of bounds", V);
          return false;
        }
  
        if (!FT->getParamType(ParamNo)->isIntegerTy()) {
          CheckFailed("'allocsize' " + Name +
                          " argument must refer to an integer parameter",
                      V);
          return false;
        }
  
        return true;
      };
  
      if (!CheckParam("element size", Args.first))
        return;
  
      if (Args.second && !CheckParam("number of elements", *Args.second))
        return;
    }
  }
  
  void Verifier::verifyFunctionMetadata(
      ArrayRef<std::pair<unsigned, MDNode *>> MDs) {
    for (const auto &Pair : MDs) {
      if (Pair.first == LLVMContext::MD_prof) {
        MDNode *MD = Pair.second;
        Assert(MD->getNumOperands() >= 2,
               "!prof annotations should have no less than 2 operands", MD);
  
        // Check first operand.
        Assert(MD->getOperand(0) != nullptr, "first operand should not be null",
               MD);
        Assert(isa<MDString>(MD->getOperand(0)),
               "expected string with name of the !prof annotation", MD);
        MDString *MDS = cast<MDString>(MD->getOperand(0));
        StringRef ProfName = MDS->getString();
        Assert(ProfName.equals("function_entry_count") ||
                   ProfName.equals("synthetic_function_entry_count"),
               "first operand should be 'function_entry_count'"
               " or 'synthetic_function_entry_count'",
               MD);
  
        // Check second operand.
        Assert(MD->getOperand(1) != nullptr, "second operand should not be null",
               MD);
        Assert(isa<ConstantAsMetadata>(MD->getOperand(1)),
               "expected integer argument to function_entry_count", MD);
      }
    }
  }
  
  void Verifier::visitConstantExprsRecursively(const Constant *EntryC) {
    if (!ConstantExprVisited.insert(EntryC).second)
      return;
  
    SmallVector<const Constant *, 16> Stack;
    Stack.push_back(EntryC);
  
    while (!Stack.empty()) {
      const Constant *C = Stack.pop_back_val();
  
      // Check this constant expression.
      if (const auto *CE = dyn_cast<ConstantExpr>(C))
        visitConstantExpr(CE);
  
      if (const auto *GV = dyn_cast<GlobalValue>(C)) {
        // Global Values get visited separately, but we do need to make sure
        // that the global value is in the correct module
        Assert(GV->getParent() == &M, "Referencing global in another module!",
               EntryC, &M, GV, GV->getParent());
        continue;
      }
  
      // Visit all sub-expressions.
      for (const Use &U : C->operands()) {
        const auto *OpC = dyn_cast<Constant>(U);
        if (!OpC)
          continue;
        if (!ConstantExprVisited.insert(OpC).second)
          continue;
        Stack.push_back(OpC);
      }
    }
  }
  
  void Verifier::visitConstantExpr(const ConstantExpr *CE) {
    if (CE->getOpcode() == Instruction::BitCast)
      Assert(CastInst::castIsValid(Instruction::BitCast, CE->getOperand(0),
                                   CE->getType()),
             "Invalid bitcast", CE);
  
    if (CE->getOpcode() == Instruction::IntToPtr ||
        CE->getOpcode() == Instruction::PtrToInt) {
      auto *PtrTy = CE->getOpcode() == Instruction::IntToPtr
                        ? CE->getType()
                        : CE->getOperand(0)->getType();
      StringRef Msg = CE->getOpcode() == Instruction::IntToPtr
                          ? "inttoptr not supported for non-integral pointers"
                          : "ptrtoint not supported for non-integral pointers";
      Assert(
          !DL.isNonIntegralPointerType(cast<PointerType>(PtrTy->getScalarType())),
          Msg);
    }
  }
  
  bool Verifier::verifyAttributeCount(AttributeList Attrs, unsigned Params) {
    // There shouldn't be more attribute sets than there are parameters plus the
    // function and return value.
    return Attrs.getNumAttrSets() <= Params + 2;
  }
  
  /// Verify that statepoint intrinsic is well formed.
  void Verifier::verifyStatepoint(const CallBase &Call) {
    assert(Call.getCalledFunction() &&
           Call.getCalledFunction()->getIntrinsicID() ==
               Intrinsic::experimental_gc_statepoint);
  
    Assert(!Call.doesNotAccessMemory() && !Call.onlyReadsMemory() &&
               !Call.onlyAccessesArgMemory(),
           "gc.statepoint must read and write all memory to preserve "
           "reordering restrictions required by safepoint semantics",
           Call);
  
    const int64_t NumPatchBytes =
        cast<ConstantInt>(Call.getArgOperand(1))->getSExtValue();
    assert(isInt<32>(NumPatchBytes) && "NumPatchBytesV is an i32!");
    Assert(NumPatchBytes >= 0,
           "gc.statepoint number of patchable bytes must be "
           "positive",
           Call);
  
    const Value *Target = Call.getArgOperand(2);
    auto *PT = dyn_cast<PointerType>(Target->getType());
    Assert(PT && PT->getElementType()->isFunctionTy(),
           "gc.statepoint callee must be of function pointer type", Call, Target);
    FunctionType *TargetFuncType = cast<FunctionType>(PT->getElementType());
  
    const int NumCallArgs = cast<ConstantInt>(Call.getArgOperand(3))->getZExtValue();
    Assert(NumCallArgs >= 0,
           "gc.statepoint number of arguments to underlying call "
           "must be positive",
           Call);
    const int NumParams = (int)TargetFuncType->getNumParams();
    if (TargetFuncType->isVarArg()) {
      Assert(NumCallArgs >= NumParams,
             "gc.statepoint mismatch in number of vararg call args", Call);
  
      // TODO: Remove this limitation
      Assert(TargetFuncType->getReturnType()->isVoidTy(),
             "gc.statepoint doesn't support wrapping non-void "
             "vararg functions yet",
             Call);
    } else
      Assert(NumCallArgs == NumParams,
             "gc.statepoint mismatch in number of call args", Call);
  
    const uint64_t Flags
      = cast<ConstantInt>(Call.getArgOperand(4))->getZExtValue();
    Assert((Flags & ~(uint64_t)StatepointFlags::MaskAll) == 0,
           "unknown flag used in gc.statepoint flags argument", Call);
  
    // Verify that the types of the call parameter arguments match
    // the type of the wrapped callee.
    AttributeList Attrs = Call.getAttributes();
    for (int i = 0; i < NumParams; i++) {
      Type *ParamType = TargetFuncType->getParamType(i);
      Type *ArgType = Call.getArgOperand(5 + i)->getType();
      Assert(ArgType == ParamType,
             "gc.statepoint call argument does not match wrapped "
             "function type",
             Call);
  
      if (TargetFuncType->isVarArg()) {
        AttributeSet ArgAttrs = Attrs.getParamAttributes(5 + i);
        Assert(!ArgAttrs.hasAttribute(Attribute::StructRet),
               "Attribute 'sret' cannot be used for vararg call arguments!",
               Call);
      }
    }
  
    const int EndCallArgsInx = 4 + NumCallArgs;
  
    const Value *NumTransitionArgsV = Call.getArgOperand(EndCallArgsInx + 1);
    Assert(isa<ConstantInt>(NumTransitionArgsV),
           "gc.statepoint number of transition arguments "
           "must be constant integer",
           Call);
    const int NumTransitionArgs =
        cast<ConstantInt>(NumTransitionArgsV)->getZExtValue();
    Assert(NumTransitionArgs >= 0,
           "gc.statepoint number of transition arguments must be positive", Call);
    const int EndTransitionArgsInx = EndCallArgsInx + 1 + NumTransitionArgs;
  
    const Value *NumDeoptArgsV = Call.getArgOperand(EndTransitionArgsInx + 1);
    Assert(isa<ConstantInt>(NumDeoptArgsV),
           "gc.statepoint number of deoptimization arguments "
           "must be constant integer",
           Call);
    const int NumDeoptArgs = cast<ConstantInt>(NumDeoptArgsV)->getZExtValue();
    Assert(NumDeoptArgs >= 0,
           "gc.statepoint number of deoptimization arguments "
           "must be positive",
           Call);
  
    const int ExpectedNumArgs =
        7 + NumCallArgs + NumTransitionArgs + NumDeoptArgs;
    Assert(ExpectedNumArgs <= (int)Call.arg_size(),
           "gc.statepoint too few arguments according to length fields", Call);
  
    // Check that the only uses of this gc.statepoint are gc.result or
    // gc.relocate calls which are tied to this statepoint and thus part
    // of the same statepoint sequence
    for (const User *U : Call.users()) {
      const CallInst *UserCall = dyn_cast<const CallInst>(U);
      Assert(UserCall, "illegal use of statepoint token", Call, U);
      if (!UserCall)
        continue;
      Assert(isa<GCRelocateInst>(UserCall) || isa<GCResultInst>(UserCall),
             "gc.result or gc.relocate are the only value uses "
             "of a gc.statepoint",
             Call, U);
      if (isa<GCResultInst>(UserCall)) {
        Assert(UserCall->getArgOperand(0) == &Call,
               "gc.result connected to wrong gc.statepoint", Call, UserCall);
      } else if (isa<GCRelocateInst>(Call)) {
        Assert(UserCall->getArgOperand(0) == &Call,
               "gc.relocate connected to wrong gc.statepoint", Call, UserCall);
      }
    }
  
    // Note: It is legal for a single derived pointer to be listed multiple
    // times.  It's non-optimal, but it is legal.  It can also happen after
    // insertion if we strip a bitcast away.
    // Note: It is really tempting to check that each base is relocated and
    // that a derived pointer is never reused as a base pointer.  This turns
    // out to be problematic since optimizations run after safepoint insertion
    // can recognize equality properties that the insertion logic doesn't know
    // about.  See example statepoint.ll in the verifier subdirectory
  }
  
  void Verifier::verifyFrameRecoverIndices() {
    for (auto &Counts : FrameEscapeInfo) {
      Function *F = Counts.first;
      unsigned EscapedObjectCount = Counts.second.first;
      unsigned MaxRecoveredIndex = Counts.second.second;
      Assert(MaxRecoveredIndex <= EscapedObjectCount,
             "all indices passed to llvm.localrecover must be less than the "
             "number of arguments passed to llvm.localescape in the parent "
             "function",
             F);
    }
  }
  
  static Instruction *getSuccPad(Instruction *Terminator) {
    BasicBlock *UnwindDest;
    if (auto *II = dyn_cast<InvokeInst>(Terminator))
      UnwindDest = II->getUnwindDest();
    else if (auto *CSI = dyn_cast<CatchSwitchInst>(Terminator))
      UnwindDest = CSI->getUnwindDest();
    else
      UnwindDest = cast<CleanupReturnInst>(Terminator)->getUnwindDest();
    return UnwindDest->getFirstNonPHI();
  }
  
  void Verifier::verifySiblingFuncletUnwinds() {
    SmallPtrSet<Instruction *, 8> Visited;
    SmallPtrSet<Instruction *, 8> Active;
    for (const auto &Pair : SiblingFuncletInfo) {
      Instruction *PredPad = Pair.first;
      if (Visited.count(PredPad))
        continue;
      Active.insert(PredPad);
      Instruction *Terminator = Pair.second;
      do {
        Instruction *SuccPad = getSuccPad(Terminator);
        if (Active.count(SuccPad)) {
          // Found a cycle; report error
          Instruction *CyclePad = SuccPad;
          SmallVector<Instruction *, 8> CycleNodes;
          do {
            CycleNodes.push_back(CyclePad);
            Instruction *CycleTerminator = SiblingFuncletInfo[CyclePad];
            if (CycleTerminator != CyclePad)
              CycleNodes.push_back(CycleTerminator);
            CyclePad = getSuccPad(CycleTerminator);
          } while (CyclePad != SuccPad);
          Assert(false, "EH pads can't handle each other's exceptions",
                 ArrayRef<Instruction *>(CycleNodes));
        }
        // Don't re-walk a node we've already checked
        if (!Visited.insert(SuccPad).second)
          break;
        // Walk to this successor if it has a map entry.
        PredPad = SuccPad;
        auto TermI = SiblingFuncletInfo.find(PredPad);
        if (TermI == SiblingFuncletInfo.end())
          break;
        Terminator = TermI->second;
        Active.insert(PredPad);
      } while (true);
      // Each node only has one successor, so we've walked all the active
      // nodes' successors.
      Active.clear();
    }
  }
  
  // visitFunction - Verify that a function is ok.
  //
  void Verifier::visitFunction(const Function &F) {
    visitGlobalValue(F);
  
    // Check function arguments.
    FunctionType *FT = F.getFunctionType();
    unsigned NumArgs = F.arg_size();
  
    Assert(&Context == &F.getContext(),
           "Function context does not match Module context!", &F);
  
    Assert(!F.hasCommonLinkage(), "Functions may not have common linkage", &F);
    Assert(FT->getNumParams() == NumArgs,
           "# formal arguments must match # of arguments for function type!", &F,
           FT);
    Assert(F.getReturnType()->isFirstClassType() ||
               F.getReturnType()->isVoidTy() || F.getReturnType()->isStructTy(),
           "Functions cannot return aggregate values!", &F);
  
    Assert(!F.hasStructRetAttr() || F.getReturnType()->isVoidTy(),
           "Invalid struct return type!", &F);
  
    AttributeList Attrs = F.getAttributes();
  
    Assert(verifyAttributeCount(Attrs, FT->getNumParams()),
           "Attribute after last parameter!", &F);
  
    bool isLLVMdotName = F.getName().size() >= 5 &&
                         F.getName().substr(0, 5) == "llvm.";
  
    // Check function attributes.
    verifyFunctionAttrs(FT, Attrs, &F, isLLVMdotName);
  
    // On function declarations/definitions, we do not support the builtin
    // attribute. We do not check this in VerifyFunctionAttrs since that is
    // checking for Attributes that can/can not ever be on functions.
    Assert(!Attrs.hasFnAttribute(Attribute::Builtin),
           "Attribute 'builtin' can only be applied to a callsite.", &F);
  
    // Check that this function meets the restrictions on this calling convention.
    // Sometimes varargs is used for perfectly forwarding thunks, so some of these
    // restrictions can be lifted.
    switch (F.getCallingConv()) {
    default:
    case CallingConv::C:
      break;
    case CallingConv::AMDGPU_KERNEL:
    case CallingConv::SPIR_KERNEL:
      Assert(F.getReturnType()->isVoidTy(),
             "Calling convention requires void return type", &F);
      LLVM_FALLTHROUGH;
    case CallingConv::AMDGPU_VS:
    case CallingConv::AMDGPU_HS:
    case CallingConv::AMDGPU_GS:
    case CallingConv::AMDGPU_PS:
    case CallingConv::AMDGPU_CS:
      Assert(!F.hasStructRetAttr(),
             "Calling convention does not allow sret", &F);
      LLVM_FALLTHROUGH;
    case CallingConv::Fast:
    case CallingConv::Cold:
    case CallingConv::Intel_OCL_BI:
    case CallingConv::PTX_Kernel:
    case CallingConv::PTX_Device:
      Assert(!F.isVarArg(), "Calling convention does not support varargs or "
                            "perfect forwarding!",
             &F);
      break;
    }
  
    // Check that the argument values match the function type for this function...
    unsigned i = 0;
    for (const Argument &Arg : F.args()) {
      Assert(Arg.getType() == FT->getParamType(i),
             "Argument value does not match function argument type!", &Arg,
             FT->getParamType(i));
      Assert(Arg.getType()->isFirstClassType(),
             "Function arguments must have first-class types!", &Arg);
      if (!isLLVMdotName) {
        Assert(!Arg.getType()->isMetadataTy(),
               "Function takes metadata but isn't an intrinsic", &Arg, &F);
        Assert(!Arg.getType()->isTokenTy(),
               "Function takes token but isn't an intrinsic", &Arg, &F);
      }
  
      // Check that swifterror argument is only used by loads and stores.
      if (Attrs.hasParamAttribute(i, Attribute::SwiftError)) {
        verifySwiftErrorValue(&Arg);
      }
      ++i;
    }
  
    if (!isLLVMdotName)
      Assert(!F.getReturnType()->isTokenTy(),
             "Functions returns a token but isn't an intrinsic", &F);
  
    // Get the function metadata attachments.
    SmallVector<std::pair<unsigned, MDNode *>, 4> MDs;
    F.getAllMetadata(MDs);
    assert(F.hasMetadata() != MDs.empty() && "Bit out-of-sync");
    verifyFunctionMetadata(MDs);
  
    // Check validity of the personality function
    if (F.hasPersonalityFn()) {
      auto *Per = dyn_cast<Function>(F.getPersonalityFn()->stripPointerCasts());
      if (Per)
        Assert(Per->getParent() == F.getParent(),
               "Referencing personality function in another module!",
               &F, F.getParent(), Per, Per->getParent());
    }
  
    if (F.isMaterializable()) {
      // Function has a body somewhere we can't see.
      Assert(MDs.empty(), "unmaterialized function cannot have metadata", &F,
             MDs.empty() ? nullptr : MDs.front().second);
    } else if (F.isDeclaration()) {
      for (const auto &I : MDs) {
        // This is used for call site debug information.
        AssertDI(I.first != LLVMContext::MD_dbg ||
                     !cast<DISubprogram>(I.second)->isDistinct(),
                 "function declaration may only have a unique !dbg attachment",
                 &F);
        Assert(I.first != LLVMContext::MD_prof,
               "function declaration may not have a !prof attachment", &F);
  
        // Verify the metadata itself.
        visitMDNode(*I.second);
      }
      Assert(!F.hasPersonalityFn(),
             "Function declaration shouldn't have a personality routine", &F);
    } else {
      // Verify that this function (which has a body) is not named "llvm.*".  It
      // is not legal to define intrinsics.
      Assert(!isLLVMdotName, "llvm intrinsics cannot be defined!", &F);
  
      // Check the entry node
      const BasicBlock *Entry = &F.getEntryBlock();
      Assert(pred_empty(Entry),
             "Entry block to function must not have predecessors!", Entry);
  
      // The address of the entry block cannot be taken, unless it is dead.
      if (Entry->hasAddressTaken()) {
        Assert(!BlockAddress::lookup(Entry)->isConstantUsed(),
               "blockaddress may not be used with the entry block!", Entry);
      }
  
      unsigned NumDebugAttachments = 0, NumProfAttachments = 0;
      // Visit metadata attachments.
      for (const auto &I : MDs) {
        // Verify that the attachment is legal.
        switch (I.first) {
        default:
          break;
        case LLVMContext::MD_dbg: {
          ++NumDebugAttachments;
          AssertDI(NumDebugAttachments == 1,
                   "function must have a single !dbg attachment", &F, I.second);
          AssertDI(isa<DISubprogram>(I.second),
                   "function !dbg attachment must be a subprogram", &F, I.second);
          auto *SP = cast<DISubprogram>(I.second);
          const Function *&AttachedTo = DISubprogramAttachments[SP];
          AssertDI(!AttachedTo || AttachedTo == &F,
                   "DISubprogram attached to more than one function", SP, &F);
          AttachedTo = &F;
          break;
        }
        case LLVMContext::MD_prof:
          ++NumProfAttachments;
          Assert(NumProfAttachments == 1,
                 "function must have a single !prof attachment", &F, I.second);
          break;
        }
  
        // Verify the metadata itself.
        visitMDNode(*I.second);
      }
    }
  
    // If this function is actually an intrinsic, verify that it is only used in
    // direct call/invokes, never having its "address taken".
    // Only do this if the module is materialized, otherwise we don't have all the
    // uses.
    if (F.getIntrinsicID() && F.getParent()->isMaterialized()) {
      const User *U;
      if (F.hasAddressTaken(&U))
        Assert(false, "Invalid user of intrinsic instruction!", U);
    }
  
    auto *N = F.getSubprogram();
    HasDebugInfo = (N != nullptr);
    if (!HasDebugInfo)
      return;
  
    // Check that all !dbg attachments lead to back to N (or, at least, another
    // subprogram that describes the same function).
    //
    // FIXME: Check this incrementally while visiting !dbg attachments.
    // FIXME: Only check when N is the canonical subprogram for F.
    SmallPtrSet<const MDNode *, 32> Seen;
    auto VisitDebugLoc = [&](const Instruction &I, const MDNode *Node) {
      // Be careful about using DILocation here since we might be dealing with
      // broken code (this is the Verifier after all).
      const DILocation *DL = dyn_cast_or_null<DILocation>(Node);
      if (!DL)
        return;
      if (!Seen.insert(DL).second)
        return;
  
      Metadata *Parent = DL->getRawScope();
      AssertDI(Parent && isa<DILocalScope>(Parent),
               "DILocation's scope must be a DILocalScope", N, &F, &I, DL,
               Parent);
      DILocalScope *Scope = DL->getInlinedAtScope();
      if (Scope && !Seen.insert(Scope).second)
        return;
  
      DISubprogram *SP = Scope ? Scope->getSubprogram() : nullptr;
  
      // Scope and SP could be the same MDNode and we don't want to skip
      // validation in that case
      if (SP && ((Scope != SP) && !Seen.insert(SP).second))
        return;
  
      // FIXME: Once N is canonical, check "SP == &N".
      AssertDI(SP->describes(&F),
               "!dbg attachment points at wrong subprogram for function", N, &F,
               &I, DL, Scope, SP);
    };
    for (auto &BB : F)
      for (auto &I : BB) {
        VisitDebugLoc(I, I.getDebugLoc().getAsMDNode());
        // The llvm.loop annotations also contain two DILocations.
        if (auto MD = I.getMetadata(LLVMContext::MD_loop))
          for (unsigned i = 1; i < MD->getNumOperands(); ++i)
            VisitDebugLoc(I, dyn_cast_or_null<MDNode>(MD->getOperand(i)));
        if (BrokenDebugInfo)
          return;
      }
  }
  
  // verifyBasicBlock - Verify that a basic block is well formed...
  //
  void Verifier::visitBasicBlock(BasicBlock &BB) {
    InstsInThisBlock.clear();
  
    // Ensure that basic blocks have terminators!
    Assert(BB.getTerminator(), "Basic Block does not have terminator!", &BB);
  
    // Check constraints that this basic block imposes on all of the PHI nodes in
    // it.
    if (isa<PHINode>(BB.front())) {
      SmallVector<BasicBlock*, 8> Preds(pred_begin(&BB), pred_end(&BB));
      SmallVector<std::pair<BasicBlock*, Value*>, 8> Values;
      llvm::sort(Preds);
      for (const PHINode &PN : BB.phis()) {
        // Ensure that PHI nodes have at least one entry!
        Assert(PN.getNumIncomingValues() != 0,
               "PHI nodes must have at least one entry.  If the block is dead, "
               "the PHI should be removed!",
               &PN);
        Assert(PN.getNumIncomingValues() == Preds.size(),
               "PHINode should have one entry for each predecessor of its "
               "parent basic block!",
               &PN);
  
        // Get and sort all incoming values in the PHI node...
        Values.clear();
        Values.reserve(PN.getNumIncomingValues());
        for (unsigned i = 0, e = PN.getNumIncomingValues(); i != e; ++i)
          Values.push_back(
              std::make_pair(PN.getIncomingBlock(i), PN.getIncomingValue(i)));
        llvm::sort(Values);
  
        for (unsigned i = 0, e = Values.size(); i != e; ++i) {
          // Check to make sure that if there is more than one entry for a
          // particular basic block in this PHI node, that the incoming values are
          // all identical.
          //
          Assert(i == 0 || Values[i].first != Values[i - 1].first ||
                     Values[i].second == Values[i - 1].second,
                 "PHI node has multiple entries for the same basic block with "
                 "different incoming values!",
                 &PN, Values[i].first, Values[i].second, Values[i - 1].second);
  
          // Check to make sure that the predecessors and PHI node entries are
          // matched up.
          Assert(Values[i].first == Preds[i],
                 "PHI node entries do not match predecessors!", &PN,
                 Values[i].first, Preds[i]);
        }
      }
    }
  
    // Check that all instructions have their parent pointers set up correctly.
    for (auto &I : BB)
    {
      Assert(I.getParent() == &BB, "Instruction has bogus parent pointer!");
    }
  }
  
  void Verifier::visitTerminator(Instruction &I) {
    // Ensure that terminators only exist at the end of the basic block.
    Assert(&I == I.getParent()->getTerminator(),
           "Terminator found in the middle of a basic block!", I.getParent());
    visitInstruction(I);
  }
  
  void Verifier::visitBranchInst(BranchInst &BI) {
    if (BI.isConditional()) {
      Assert(BI.getCondition()->getType()->isIntegerTy(1),
             "Branch condition is not 'i1' type!", &BI, BI.getCondition());
    }
    visitTerminator(BI);
  }
  
  void Verifier::visitReturnInst(ReturnInst &RI) {
    Function *F = RI.getParent()->getParent();
    unsigned N = RI.getNumOperands();
    if (F->getReturnType()->isVoidTy())
      Assert(N == 0,
             "Found return instr that returns non-void in Function of void "
             "return type!",
             &RI, F->getReturnType());
    else
      Assert(N == 1 && F->getReturnType() == RI.getOperand(0)->getType(),
             "Function return type does not match operand "
             "type of return inst!",
             &RI, F->getReturnType());
  
    // Check to make sure that the return value has necessary properties for
    // terminators...
    visitTerminator(RI);
  }
  
  void Verifier::visitSwitchInst(SwitchInst &SI) {
    // Check to make sure that all of the constants in the switch instruction
    // have the same type as the switched-on value.
    Type *SwitchTy = SI.getCondition()->getType();
    SmallPtrSet<ConstantInt*, 32> Constants;
    for (auto &Case : SI.cases()) {
      Assert(Case.getCaseValue()->getType() == SwitchTy,
             "Switch constants must all be same type as switch value!", &SI);
      Assert(Constants.insert(Case.getCaseValue()).second,
             "Duplicate integer as switch case", &SI, Case.getCaseValue());
    }
  
    visitTerminator(SI);
  }
  
  void Verifier::visitIndirectBrInst(IndirectBrInst &BI) {
    Assert(BI.getAddress()->getType()->isPointerTy(),
           "Indirectbr operand must have pointer type!", &BI);
    for (unsigned i = 0, e = BI.getNumDestinations(); i != e; ++i)
      Assert(BI.getDestination(i)->getType()->isLabelTy(),
             "Indirectbr destinations must all have pointer type!", &BI);
  
    visitTerminator(BI);
  }
  
  void Verifier::visitCallBrInst(CallBrInst &CBI) {
    Assert(CBI.isInlineAsm(), "Callbr is currently only used for asm-goto!",
           &CBI);
    Assert(CBI.getType()->isVoidTy(), "Callbr return value is not supported!",
           &CBI);
    for (unsigned i = 0, e = CBI.getNumSuccessors(); i != e; ++i)
      Assert(CBI.getSuccessor(i)->getType()->isLabelTy(),
             "Callbr successors must all have pointer type!", &CBI);
    for (unsigned i = 0, e = CBI.getNumOperands(); i != e; ++i) {
      Assert(i >= CBI.getNumArgOperands() || !isa<BasicBlock>(CBI.getOperand(i)),
             "Using an unescaped label as a callbr argument!", &CBI);
      if (isa<BasicBlock>(CBI.getOperand(i)))
        for (unsigned j = i + 1; j != e; ++j)
          Assert(CBI.getOperand(i) != CBI.getOperand(j),
                 "Duplicate callbr destination!", &CBI);
    }
  
    visitTerminator(CBI);
  }
  
  void Verifier::visitSelectInst(SelectInst &SI) {
    Assert(!SelectInst::areInvalidOperands(SI.getOperand(0), SI.getOperand(1),
                                           SI.getOperand(2)),
           "Invalid operands for select instruction!", &SI);
  
    Assert(SI.getTrueValue()->getType() == SI.getType(),
           "Select values must have same type as select instruction!", &SI);
    visitInstruction(SI);
  }
  
  /// visitUserOp1 - User defined operators shouldn't live beyond the lifetime of
  /// a pass, if any exist, it's an error.
  ///
  void Verifier::visitUserOp1(Instruction &I) {
    Assert(false, "User-defined operators should not live outside of a pass!", &I);
  }
  
  void Verifier::visitTruncInst(TruncInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    // Get the size of the types in bits, we'll need this later
    unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
    unsigned DestBitSize = DestTy->getScalarSizeInBits();
  
    Assert(SrcTy->isIntOrIntVectorTy(), "Trunc only operates on integer", &I);
    Assert(DestTy->isIntOrIntVectorTy(), "Trunc only produces integer", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(),
           "trunc source and destination must both be a vector or neither", &I);
    Assert(SrcBitSize > DestBitSize, "DestTy too big for Trunc", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitZExtInst(ZExtInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    // Get the size of the types in bits, we'll need this later
    Assert(SrcTy->isIntOrIntVectorTy(), "ZExt only operates on integer", &I);
    Assert(DestTy->isIntOrIntVectorTy(), "ZExt only produces an integer", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(),
           "zext source and destination must both be a vector or neither", &I);
    unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
    unsigned DestBitSize = DestTy->getScalarSizeInBits();
  
    Assert(SrcBitSize < DestBitSize, "Type too small for ZExt", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitSExtInst(SExtInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    // Get the size of the types in bits, we'll need this later
    unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
    unsigned DestBitSize = DestTy->getScalarSizeInBits();
  
    Assert(SrcTy->isIntOrIntVectorTy(), "SExt only operates on integer", &I);
    Assert(DestTy->isIntOrIntVectorTy(), "SExt only produces an integer", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(),
           "sext source and destination must both be a vector or neither", &I);
    Assert(SrcBitSize < DestBitSize, "Type too small for SExt", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitFPTruncInst(FPTruncInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
    // Get the size of the types in bits, we'll need this later
    unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
    unsigned DestBitSize = DestTy->getScalarSizeInBits();
  
    Assert(SrcTy->isFPOrFPVectorTy(), "FPTrunc only operates on FP", &I);
    Assert(DestTy->isFPOrFPVectorTy(), "FPTrunc only produces an FP", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(),
           "fptrunc source and destination must both be a vector or neither", &I);
    Assert(SrcBitSize > DestBitSize, "DestTy too big for FPTrunc", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitFPExtInst(FPExtInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    // Get the size of the types in bits, we'll need this later
    unsigned SrcBitSize = SrcTy->getScalarSizeInBits();
    unsigned DestBitSize = DestTy->getScalarSizeInBits();
  
    Assert(SrcTy->isFPOrFPVectorTy(), "FPExt only operates on FP", &I);
    Assert(DestTy->isFPOrFPVectorTy(), "FPExt only produces an FP", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(),
           "fpext source and destination must both be a vector or neither", &I);
    Assert(SrcBitSize < DestBitSize, "DestTy too small for FPExt", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitUIToFPInst(UIToFPInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    bool SrcVec = SrcTy->isVectorTy();
    bool DstVec = DestTy->isVectorTy();
  
    Assert(SrcVec == DstVec,
           "UIToFP source and dest must both be vector or scalar", &I);
    Assert(SrcTy->isIntOrIntVectorTy(),
           "UIToFP source must be integer or integer vector", &I);
    Assert(DestTy->isFPOrFPVectorTy(), "UIToFP result must be FP or FP vector",
           &I);
  
    if (SrcVec && DstVec)
      Assert(cast<VectorType>(SrcTy)->getNumElements() ==
                 cast<VectorType>(DestTy)->getNumElements(),
             "UIToFP source and dest vector length mismatch", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitSIToFPInst(SIToFPInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    bool SrcVec = SrcTy->isVectorTy();
    bool DstVec = DestTy->isVectorTy();
  
    Assert(SrcVec == DstVec,
           "SIToFP source and dest must both be vector or scalar", &I);
    Assert(SrcTy->isIntOrIntVectorTy(),
           "SIToFP source must be integer or integer vector", &I);
    Assert(DestTy->isFPOrFPVectorTy(), "SIToFP result must be FP or FP vector",
           &I);
  
    if (SrcVec && DstVec)
      Assert(cast<VectorType>(SrcTy)->getNumElements() ==
                 cast<VectorType>(DestTy)->getNumElements(),
             "SIToFP source and dest vector length mismatch", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitFPToUIInst(FPToUIInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    bool SrcVec = SrcTy->isVectorTy();
    bool DstVec = DestTy->isVectorTy();
  
    Assert(SrcVec == DstVec,
           "FPToUI source and dest must both be vector or scalar", &I);
    Assert(SrcTy->isFPOrFPVectorTy(), "FPToUI source must be FP or FP vector",
           &I);
    Assert(DestTy->isIntOrIntVectorTy(),
           "FPToUI result must be integer or integer vector", &I);
  
    if (SrcVec && DstVec)
      Assert(cast<VectorType>(SrcTy)->getNumElements() ==
                 cast<VectorType>(DestTy)->getNumElements(),
             "FPToUI source and dest vector length mismatch", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitFPToSIInst(FPToSIInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    bool SrcVec = SrcTy->isVectorTy();
    bool DstVec = DestTy->isVectorTy();
  
    Assert(SrcVec == DstVec,
           "FPToSI source and dest must both be vector or scalar", &I);
    Assert(SrcTy->isFPOrFPVectorTy(), "FPToSI source must be FP or FP vector",
           &I);
    Assert(DestTy->isIntOrIntVectorTy(),
           "FPToSI result must be integer or integer vector", &I);
  
    if (SrcVec && DstVec)
      Assert(cast<VectorType>(SrcTy)->getNumElements() ==
                 cast<VectorType>(DestTy)->getNumElements(),
             "FPToSI source and dest vector length mismatch", &I);
  
    visitInstruction(I);
  }
  
  void Verifier::visitPtrToIntInst(PtrToIntInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    Assert(SrcTy->isPtrOrPtrVectorTy(), "PtrToInt source must be pointer", &I);
  
    if (auto *PTy = dyn_cast<PointerType>(SrcTy->getScalarType()))
      Assert(!DL.isNonIntegralPointerType(PTy),
             "ptrtoint not supported for non-integral pointers");
  
    Assert(DestTy->isIntOrIntVectorTy(), "PtrToInt result must be integral", &I);
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(), "PtrToInt type mismatch",
           &I);
  
    if (SrcTy->isVectorTy()) {
      VectorType *VSrc = dyn_cast<VectorType>(SrcTy);
      VectorType *VDest = dyn_cast<VectorType>(DestTy);
      Assert(VSrc->getNumElements() == VDest->getNumElements(),
             "PtrToInt Vector width mismatch", &I);
    }
  
    visitInstruction(I);
  }
  
  void Verifier::visitIntToPtrInst(IntToPtrInst &I) {
    // Get the source and destination types
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    Assert(SrcTy->isIntOrIntVectorTy(),
           "IntToPtr source must be an integral", &I);
    Assert(DestTy->isPtrOrPtrVectorTy(), "IntToPtr result must be a pointer", &I);
  
    if (auto *PTy = dyn_cast<PointerType>(DestTy->getScalarType()))
      Assert(!DL.isNonIntegralPointerType(PTy),
             "inttoptr not supported for non-integral pointers");
  
    Assert(SrcTy->isVectorTy() == DestTy->isVectorTy(), "IntToPtr type mismatch",
           &I);
    if (SrcTy->isVectorTy()) {
      VectorType *VSrc = dyn_cast<VectorType>(SrcTy);
      VectorType *VDest = dyn_cast<VectorType>(DestTy);
      Assert(VSrc->getNumElements() == VDest->getNumElements(),
             "IntToPtr Vector width mismatch", &I);
    }
    visitInstruction(I);
  }
  
  void Verifier::visitBitCastInst(BitCastInst &I) {
    Assert(
        CastInst::castIsValid(Instruction::BitCast, I.getOperand(0), I.getType()),
        "Invalid bitcast", &I);
    visitInstruction(I);
  }
  
  void Verifier::visitAddrSpaceCastInst(AddrSpaceCastInst &I) {
    Type *SrcTy = I.getOperand(0)->getType();
    Type *DestTy = I.getType();
  
    Assert(SrcTy->isPtrOrPtrVectorTy(), "AddrSpaceCast source must be a pointer",
           &I);
    Assert(DestTy->isPtrOrPtrVectorTy(), "AddrSpaceCast result must be a pointer",
           &I);
    Assert(SrcTy->getPointerAddressSpace() != DestTy->getPointerAddressSpace(),
           "AddrSpaceCast must be between different address spaces", &I);
    if (SrcTy->isVectorTy())
      Assert(SrcTy->getVectorNumElements() == DestTy->getVectorNumElements(),
             "AddrSpaceCast vector pointer number of elements mismatch", &I);
    visitInstruction(I);
  }
  
  /// visitPHINode - Ensure that a PHI node is well formed.
  ///
  void Verifier::visitPHINode(PHINode &PN) {
    // Ensure that the PHI nodes are all grouped together at the top of the block.
    // This can be tested by checking whether the instruction before this is
    // either nonexistent (because this is begin()) or is a PHI node.  If not,
    // then there is some other instruction before a PHI.
    Assert(&PN == &PN.getParent()->front() ||
               isa<PHINode>(--BasicBlock::iterator(&PN)),
           "PHI nodes not grouped at top of basic block!", &PN, PN.getParent());
  
    // Check that a PHI doesn't yield a Token.
    Assert(!PN.getType()->isTokenTy(), "PHI nodes cannot have token type!");
  
    // Check that all of the values of the PHI node have the same type as the
    // result, and that the incoming blocks are really basic blocks.
    for (Value *IncValue : PN.incoming_values()) {
      Assert(PN.getType() == IncValue->getType(),
             "PHI node operands are not the same type as the result!", &PN);
    }
  
    // All other PHI node constraints are checked in the visitBasicBlock method.
  
    visitInstruction(PN);
  }
  
  void Verifier::visitCallBase(CallBase &Call) {
    Assert(Call.getCalledValue()->getType()->isPointerTy(),
           "Called function must be a pointer!", Call);
    PointerType *FPTy = cast<PointerType>(Call.getCalledValue()->getType());
  
    Assert(FPTy->getElementType()->isFunctionTy(),
           "Called function is not pointer to function type!", Call);
  
    Assert(FPTy->getElementType() == Call.getFunctionType(),
           "Called function is not the same type as the call!", Call);
  
    FunctionType *FTy = Call.getFunctionType();
  
    // Verify that the correct number of arguments are being passed
    if (FTy->isVarArg())
      Assert(Call.arg_size() >= FTy->getNumParams(),
             "Called function requires more parameters than were provided!",
             Call);
    else
      Assert(Call.arg_size() == FTy->getNumParams(),
             "Incorrect number of arguments passed to called function!", Call);
  
    // Verify that all arguments to the call match the function type.
    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i)
      Assert(Call.getArgOperand(i)->getType() == FTy->getParamType(i),
             "Call parameter type does not match function signature!",
             Call.getArgOperand(i), FTy->getParamType(i), Call);
  
    AttributeList Attrs = Call.getAttributes();
  
    Assert(verifyAttributeCount(Attrs, Call.arg_size()),
           "Attribute after last parameter!", Call);
  
    bool IsIntrinsic = Call.getCalledFunction() &&
                       Call.getCalledFunction()->getName().startswith("llvm.");
  
    Function *Callee
      = dyn_cast<Function>(Call.getCalledValue()->stripPointerCasts());
  
    if (Attrs.hasAttribute(AttributeList::FunctionIndex, Attribute::Speculatable)) {
      // Don't allow speculatable on call sites, unless the underlying function
      // declaration is also speculatable.
      Assert(Callee && Callee->isSpeculatable(),
             "speculatable attribute may not apply to call sites", Call);
    }
  
    // Verify call attributes.
    verifyFunctionAttrs(FTy, Attrs, &Call, IsIntrinsic);
  
    // Conservatively check the inalloca argument.
    // We have a bug if we can find that there is an underlying alloca without
    // inalloca.
    if (Call.hasInAllocaArgument()) {
      Value *InAllocaArg = Call.getArgOperand(FTy->getNumParams() - 1);
      if (auto AI = dyn_cast<AllocaInst>(InAllocaArg->stripInBoundsOffsets()))
        Assert(AI->isUsedWithInAlloca(),
               "inalloca argument for call has mismatched alloca", AI, Call);
    }
  
    // For each argument of the callsite, if it has the swifterror argument,
    // make sure the underlying alloca/parameter it comes from has a swifterror as
    // well.
    for (unsigned i = 0, e = FTy->getNumParams(); i != e; ++i) {
      if (Call.paramHasAttr(i, Attribute::SwiftError)) {
        Value *SwiftErrorArg = Call.getArgOperand(i);
        if (auto AI = dyn_cast<AllocaInst>(SwiftErrorArg->stripInBoundsOffsets())) {
          Assert(AI->isSwiftError(),
                 "swifterror argument for call has mismatched alloca", AI, Call);
          continue;
        }
        auto ArgI = dyn_cast<Argument>(SwiftErrorArg);
        Assert(ArgI,
               "swifterror argument should come from an alloca or parameter",
               SwiftErrorArg, Call);
        Assert(ArgI->hasSwiftErrorAttr(),
               "swifterror argument for call has mismatched parameter", ArgI,
               Call);
      }
  
      if (Attrs.hasParamAttribute(i, Attribute::ImmArg)) {
        // Don't allow immarg on call sites, unless the underlying declaration
        // also has the matching immarg.
        Assert(Callee && Callee->hasParamAttribute(i, Attribute::ImmArg),
               "immarg may not apply only to call sites",
               Call.getArgOperand(i), Call);
      }
  
      if (Call.paramHasAttr(i, Attribute::ImmArg)) {
        Value *ArgVal = Call.getArgOperand(i);
        Assert(isa<ConstantInt>(ArgVal) || isa<ConstantFP>(ArgVal),
               "immarg operand has non-immediate parameter", ArgVal, Call);
      }
    }
  
    if (FTy->isVarArg()) {
      // FIXME? is 'nest' even legal here?
      bool SawNest = false;
      bool SawReturned = false;
  
      for (unsigned Idx = 0; Idx < FTy->getNumParams(); ++Idx) {
        if (Attrs.hasParamAttribute(Idx, Attribute::Nest))
          SawNest = true;
        if (Attrs.hasParamAttribute(Idx, Attribute::Returned))
          SawReturned = true;
      }
  
      // Check attributes on the varargs part.
      for (unsigned Idx = FTy->getNumParams(); Idx < Call.arg_size(); ++Idx) {
        Type *Ty = Call.getArgOperand(Idx)->getType();
        AttributeSet ArgAttrs = Attrs.getParamAttributes(Idx);
        verifyParameterAttrs(ArgAttrs, Ty, &Call);
  
        if (ArgAttrs.hasAttribute(Attribute::Nest)) {
          Assert(!SawNest, "More than one parameter has attribute nest!", Call);
          SawNest = true;
        }
  
        if (ArgAttrs.hasAttribute(Attribute::Returned)) {
          Assert(!SawReturned, "More than one parameter has attribute returned!",
                 Call);
          Assert(Ty->canLosslesslyBitCastTo(FTy->getReturnType()),
                 "Incompatible argument and return types for 'returned' "
                 "attribute",
                 Call);
          SawReturned = true;
        }
  
        // Statepoint intrinsic is vararg but the wrapped function may be not.
        // Allow sret here and check the wrapped function in verifyStatepoint.
        if (!Call.getCalledFunction() ||
            Call.getCalledFunction()->getIntrinsicID() !=
                Intrinsic::experimental_gc_statepoint)
          Assert(!ArgAttrs.hasAttribute(Attribute::StructRet),
                 "Attribute 'sret' cannot be used for vararg call arguments!",
                 Call);
  
        if (ArgAttrs.hasAttribute(Attribute::InAlloca))
          Assert(Idx == Call.arg_size() - 1,
                 "inalloca isn't on the last argument!", Call);
      }
    }
  
    // Verify that there's no metadata unless it's a direct call to an intrinsic.
    if (!IsIntrinsic) {
      for (Type *ParamTy : FTy->params()) {
        Assert(!ParamTy->isMetadataTy(),
               "Function has metadata parameter but isn't an intrinsic", Call);
        Assert(!ParamTy->isTokenTy(),
               "Function has token parameter but isn't an intrinsic", Call);
      }
    }
  
    // Verify that indirect calls don't return tokens.
    if (!Call.getCalledFunction())
      Assert(!FTy->getReturnType()->isTokenTy(),
             "Return type cannot be token for indirect call!");
  
    if (Function *F = Call.getCalledFunction())
      if (Intrinsic::ID ID = (Intrinsic::ID)F->getIntrinsicID())
        visitIntrinsicCall(ID, Call);
  
    // Verify that a callsite has at most one "deopt", at most one "funclet" and
    // at most one "gc-transition" operand bundle.
    bool FoundDeoptBundle = false, FoundFuncletBundle = false,
         FoundGCTransitionBundle = false;
    for (unsigned i = 0, e = Call.getNumOperandBundles(); i < e; ++i) {
      OperandBundleUse BU = Call.getOperandBundleAt(i);
      uint32_t Tag = BU.getTagID();
      if (Tag == LLVMContext::OB_deopt) {
        Assert(!FoundDeoptBundle, "Multiple deopt operand bundles", Call);
        FoundDeoptBundle = true;
      } else if (Tag == LLVMContext::OB_gc_transition) {
        Assert(!FoundGCTransitionBundle, "Multiple gc-transition operand bundles",
               Call);
        FoundGCTransitionBundle = true;
      } else if (Tag == LLVMContext::OB_funclet) {
        Assert(!FoundFuncletBundle, "Multiple funclet operand bundles", Call);
        FoundFuncletBundle = true;
        Assert(BU.Inputs.size() == 1,
               "Expected exactly one funclet bundle operand", Call);
        Assert(isa<FuncletPadInst>(BU.Inputs.front()),
               "Funclet bundle operands should correspond to a FuncletPadInst",
               Call);
      }
    }
  
    // Verify that each inlinable callsite of a debug-info-bearing function in a
    // debug-info-bearing function has a debug location attached to it. Failure to
    // do so causes assertion failures when the inliner sets up inline scope info.
    if (Call.getFunction()->getSubprogram() && Call.getCalledFunction() &&
        Call.getCalledFunction()->getSubprogram())
      AssertDI(Call.getDebugLoc(),
               "inlinable function call in a function with "
               "debug info must have a !dbg location",
               Call);
  
    visitInstruction(Call);
  }
  
  /// Two types are "congruent" if they are identical, or if they are both pointer
  /// types with different pointee types and the same address space.
  static bool isTypeCongruent(Type *L, Type *R) {
    if (L == R)
      return true;
    PointerType *PL = dyn_cast<PointerType>(L);
    PointerType *PR = dyn_cast<PointerType>(R);
    if (!PL || !PR)
      return false;
    return PL->getAddressSpace() == PR->getAddressSpace();
  }
  
  static AttrBuilder getParameterABIAttributes(int I, AttributeList Attrs) {
    static const Attribute::AttrKind ABIAttrs[] = {
        Attribute::StructRet, Attribute::ByVal, Attribute::InAlloca,
        Attribute::InReg, Attribute::Returned, Attribute::SwiftSelf,
        Attribute::SwiftError};
    AttrBuilder Copy;
    for (auto AK : ABIAttrs) {
      if (Attrs.hasParamAttribute(I, AK))
        Copy.addAttribute(AK);
    }
    if (Attrs.hasParamAttribute(I, Attribute::Alignment))
      Copy.addAlignmentAttr(Attrs.getParamAlignment(I));
    return Copy;
  }
  
  void Verifier::verifyMustTailCall(CallInst &CI) {
    Assert(!CI.isInlineAsm(), "cannot use musttail call with inline asm", &CI);
  
    // - The caller and callee prototypes must match.  Pointer types of
    //   parameters or return types may differ in pointee type, but not
    //   address space.
    Function *F = CI.getParent()->getParent();
    FunctionType *CallerTy = F->getFunctionType();
    FunctionType *CalleeTy = CI.getFunctionType();
    if (!CI.getCalledFunction() || !CI.getCalledFunction()->isIntrinsic()) {
      Assert(CallerTy->getNumParams() == CalleeTy->getNumParams(),
             "cannot guarantee tail call due to mismatched parameter counts",
             &CI);
      for (int I = 0, E = CallerTy->getNumParams(); I != E; ++I) {
        Assert(
            isTypeCongruent(CallerTy->getParamType(I), CalleeTy->getParamType(I)),
            "cannot guarantee tail call due to mismatched parameter types", &CI);
      }
    }
    Assert(CallerTy->isVarArg() == CalleeTy->isVarArg(),
           "cannot guarantee tail call due to mismatched varargs", &CI);
    Assert(isTypeCongruent(CallerTy->getReturnType(), CalleeTy->getReturnType()),
           "cannot guarantee tail call due to mismatched return types", &CI);
  
    // - The calling conventions of the caller and callee must match.
    Assert(F->getCallingConv() == CI.getCallingConv(),
           "cannot guarantee tail call due to mismatched calling conv", &CI);
  
    // - All ABI-impacting function attributes, such as sret, byval, inreg,
    //   returned, and inalloca, must match.
    AttributeList CallerAttrs = F->getAttributes();
    AttributeList CalleeAttrs = CI.getAttributes();
    for (int I = 0, E = CallerTy->getNumParams(); I != E; ++I) {
      AttrBuilder CallerABIAttrs = getParameterABIAttributes(I, CallerAttrs);
      AttrBuilder CalleeABIAttrs = getParameterABIAttributes(I, CalleeAttrs);
      Assert(CallerABIAttrs == CalleeABIAttrs,
             "cannot guarantee tail call due to mismatched ABI impacting "
             "function attributes",
             &CI, CI.getOperand(I));
    }
  
    // - The call must immediately precede a :ref:`ret <i_ret>` instruction,
    //   or a pointer bitcast followed by a ret instruction.
    // - The ret instruction must return the (possibly bitcasted) value
    //   produced by the call or void.
    Value *RetVal = &CI;
    Instruction *Next = CI.getNextNode();
  
    // Handle the optional bitcast.
    if (BitCastInst *BI = dyn_cast_or_null<BitCastInst>(Next)) {
      Assert(BI->getOperand(0) == RetVal,
             "bitcast following musttail call must use the call", BI);
      RetVal = BI;
      Next = BI->getNextNode();
    }
  
    // Check the return.
    ReturnInst *Ret = dyn_cast_or_null<ReturnInst>(Next);
    Assert(Ret, "musttail call must precede a ret with an optional bitcast",
           &CI);
    Assert(!Ret->getReturnValue() || Ret->getReturnValue() == RetVal,
           "musttail call result must be returned", Ret);
  }
  
  void Verifier::visitCallInst(CallInst &CI) {
    visitCallBase(CI);
  
    if (CI.isMustTailCall())
      verifyMustTailCall(CI);
  }
  
  void Verifier::visitInvokeInst(InvokeInst &II) {
    visitCallBase(II);
  
    // Verify that the first non-PHI instruction of the unwind destination is an
    // exception handling instruction.
    Assert(
        II.getUnwindDest()->isEHPad(),
        "The unwind destination does not have an exception handling instruction!",
        &II);
  
    visitTerminator(II);
  }
  
  /// visitUnaryOperator - Check the argument to the unary operator.
  ///
  void Verifier::visitUnaryOperator(UnaryOperator &U) {
    Assert(U.getType() == U.getOperand(0)->getType(), 
           "Unary operators must have same type for"
           "operands and result!",
           &U);
  
    switch (U.getOpcode()) {
    // Check that floating-point arithmetic operators are only used with
    // floating-point operands.
    case Instruction::FNeg:
      Assert(U.getType()->isFPOrFPVectorTy(),
             "FNeg operator only works with float types!", &U);
      break;
    default:
      llvm_unreachable("Unknown UnaryOperator opcode!");
    }
  
    visitInstruction(U);
  }
  
  /// visitBinaryOperator - Check that both arguments to the binary operator are
  /// of the same type!
  ///
  void Verifier::visitBinaryOperator(BinaryOperator &B) {
    Assert(B.getOperand(0)->getType() == B.getOperand(1)->getType(),
           "Both operands to a binary operator are not of the same type!", &B);
  
    switch (B.getOpcode()) {
    // Check that integer arithmetic operators are only used with
    // integral operands.
    case Instruction::Add:
    case Instruction::Sub:
    case Instruction::Mul:
    case Instruction::SDiv:
    case Instruction::UDiv:
    case Instruction::SRem:
    case Instruction::URem:
      Assert(B.getType()->isIntOrIntVectorTy(),
             "Integer arithmetic operators only work with integral types!", &B);
      Assert(B.getType() == B.getOperand(0)->getType(),
             "Integer arithmetic operators must have same type "
             "for operands and result!",
             &B);
      break;
    // Check that floating-point arithmetic operators are only used with
    // floating-point operands.
    case Instruction::FAdd:
    case Instruction::FSub:
    case Instruction::FMul:
    case Instruction::FDiv:
    case Instruction::FRem:
      Assert(B.getType()->isFPOrFPVectorTy(),
             "Floating-point arithmetic operators only work with "
             "floating-point types!",
             &B);
      Assert(B.getType() == B.getOperand(0)->getType(),
             "Floating-point arithmetic operators must have same type "
             "for operands and result!",
             &B);
      break;
    // Check that logical operators are only used with integral operands.
    case Instruction::And:
    case Instruction::Or:
    case Instruction::Xor:
      Assert(B.getType()->isIntOrIntVectorTy(),
             "Logical operators only work with integral types!", &B);
      Assert(B.getType() == B.getOperand(0)->getType(),
             "Logical operators must have same type for operands and result!",
             &B);
      break;
    case Instruction::Shl:
    case Instruction::LShr:
    case Instruction::AShr:
      Assert(B.getType()->isIntOrIntVectorTy(),
             "Shifts only work with integral types!", &B);
      Assert(B.getType() == B.getOperand(0)->getType(),
             "Shift return type must be same as operands!", &B);
      break;
    default:
      llvm_unreachable("Unknown BinaryOperator opcode!");
    }
  
    visitInstruction(B);
  }
  
  void Verifier::visitICmpInst(ICmpInst &IC) {
    // Check that the operands are the same type
    Type *Op0Ty = IC.getOperand(0)->getType();
    Type *Op1Ty = IC.getOperand(1)->getType();
    Assert(Op0Ty == Op1Ty,
           "Both operands to ICmp instruction are not of the same type!", &IC);
    // Check that the operands are the right type
    Assert(Op0Ty->isIntOrIntVectorTy() || Op0Ty->isPtrOrPtrVectorTy(),
           "Invalid operand types for ICmp instruction", &IC);
    // Check that the predicate is valid.
    Assert(IC.isIntPredicate(),
           "Invalid predicate in ICmp instruction!", &IC);
  
    visitInstruction(IC);
  }
  
  void Verifier::visitFCmpInst(FCmpInst &FC) {
    // Check that the operands are the same type
    Type *Op0Ty = FC.getOperand(0)->getType();
    Type *Op1Ty = FC.getOperand(1)->getType();
    Assert(Op0Ty == Op1Ty,
           "Both operands to FCmp instruction are not of the same type!", &FC);
    // Check that the operands are the right type
    Assert(Op0Ty->isFPOrFPVectorTy(),
           "Invalid operand types for FCmp instruction", &FC);
    // Check that the predicate is valid.
    Assert(FC.isFPPredicate(),
           "Invalid predicate in FCmp instruction!", &FC);
  
    visitInstruction(FC);
  }
  
  void Verifier::visitExtractElementInst(ExtractElementInst &EI) {
    Assert(
        ExtractElementInst::isValidOperands(EI.getOperand(0), EI.getOperand(1)),
        "Invalid extractelement operands!", &EI);
    visitInstruction(EI);
  }
  
  void Verifier::visitInsertElementInst(InsertElementInst &IE) {
    Assert(InsertElementInst::isValidOperands(IE.getOperand(0), IE.getOperand(1),
                                              IE.getOperand(2)),
           "Invalid insertelement operands!", &IE);
    visitInstruction(IE);
  }
  
  void Verifier::visitShuffleVectorInst(ShuffleVectorInst &SV) {
    Assert(ShuffleVectorInst::isValidOperands(SV.getOperand(0), SV.getOperand(1),
                                              SV.getOperand(2)),
           "Invalid shufflevector operands!", &SV);
    visitInstruction(SV);
  }
  
  void Verifier::visitGetElementPtrInst(GetElementPtrInst &GEP) {
    Type *TargetTy = GEP.getPointerOperandType()->getScalarType();
  
    Assert(isa<PointerType>(TargetTy),
           "GEP base pointer is not a vector or a vector of pointers", &GEP);
    Assert(GEP.getSourceElementType()->isSized(), "GEP into unsized type!", &GEP);
  
    SmallVector<Value*, 16> Idxs(GEP.idx_begin(), GEP.idx_end());
    Assert(all_of(
        Idxs, [](Value* V) { return V->getType()->isIntOrIntVectorTy(); }),
        "GEP indexes must be integers", &GEP);
    Type *ElTy =
        GetElementPtrInst::getIndexedType(GEP.getSourceElementType(), Idxs);
    Assert(ElTy, "Invalid indices for GEP pointer type!", &GEP);
  
    Assert(GEP.getType()->isPtrOrPtrVectorTy() &&
               GEP.getResultElementType() == ElTy,
           "GEP is not of right type for indices!", &GEP, ElTy);
  
    if (GEP.getType()->isVectorTy()) {
      // Additional checks for vector GEPs.
      unsigned GEPWidth = GEP.getType()->getVectorNumElements();
      if (GEP.getPointerOperandType()->isVectorTy())
        Assert(GEPWidth == GEP.getPointerOperandType()->getVectorNumElements(),
               "Vector GEP result width doesn't match operand's", &GEP);
      for (Value *Idx : Idxs) {
        Type *IndexTy = Idx->getType();
        if (IndexTy->isVectorTy()) {
          unsigned IndexWidth = IndexTy->getVectorNumElements();
          Assert(IndexWidth == GEPWidth, "Invalid GEP index vector width", &GEP);
        }
        Assert(IndexTy->isIntOrIntVectorTy(),
               "All GEP indices should be of integer type");
      }
    }
  
    if (auto *PTy = dyn_cast<PointerType>(GEP.getType())) {
      Assert(GEP.getAddressSpace() == PTy->getAddressSpace(),
             "GEP address space doesn't match type", &GEP);
    }
  
    visitInstruction(GEP);
  }
  
  static bool isContiguous(const ConstantRange &A, const ConstantRange &B) {
    return A.getUpper() == B.getLower() || A.getLower() == B.getUpper();
  }
  
  void Verifier::visitRangeMetadata(Instruction &I, MDNode *Range, Type *Ty) {
    assert(Range && Range == I.getMetadata(LLVMContext::MD_range) &&
           "precondition violation");
  
    unsigned NumOperands = Range->getNumOperands();
    Assert(NumOperands % 2 == 0, "Unfinished range!", Range);
    unsigned NumRanges = NumOperands / 2;
    Assert(NumRanges >= 1, "It should have at least one range!", Range);
  
    ConstantRange LastRange(1, true); // Dummy initial value
    for (unsigned i = 0; i < NumRanges; ++i) {
      ConstantInt *Low =
          mdconst::dyn_extract<ConstantInt>(Range->getOperand(2 * i));
      Assert(Low, "The lower limit must be an integer!", Low);
      ConstantInt *High =
          mdconst::dyn_extract<ConstantInt>(Range->getOperand(2 * i + 1));
      Assert(High, "The upper limit must be an integer!", High);
      Assert(High->getType() == Low->getType() && High->getType() == Ty,
             "Range types must match instruction type!", &I);
  
      APInt HighV = High->getValue();
      APInt LowV = Low->getValue();
      ConstantRange CurRange(LowV, HighV);
      Assert(!CurRange.isEmptySet() && !CurRange.isFullSet(),
             "Range must not be empty!", Range);
      if (i != 0) {
        Assert(CurRange.intersectWith(LastRange).isEmptySet(),
               "Intervals are overlapping", Range);
        Assert(LowV.sgt(LastRange.getLower()), "Intervals are not in order",
               Range);
        Assert(!isContiguous(CurRange, LastRange), "Intervals are contiguous",
               Range);
      }
      LastRange = ConstantRange(LowV, HighV);
    }
    if (NumRanges > 2) {
      APInt FirstLow =
          mdconst::dyn_extract<ConstantInt>(Range->getOperand(0))->getValue();
      APInt FirstHigh =
          mdconst::dyn_extract<ConstantInt>(Range->getOperand(1))->getValue();
      ConstantRange FirstRange(FirstLow, FirstHigh);
      Assert(FirstRange.intersectWith(LastRange).isEmptySet(),
             "Intervals are overlapping", Range);
      Assert(!isContiguous(FirstRange, LastRange), "Intervals are contiguous",
             Range);
    }
  }
  
  void Verifier::checkAtomicMemAccessSize(Type *Ty, const Instruction *I) {
    unsigned Size = DL.getTypeSizeInBits(Ty);
    Assert(Size >= 8, "atomic memory access' size must be byte-sized", Ty, I);
    Assert(!(Size & (Size - 1)),
           "atomic memory access' operand must have a power-of-two size", Ty, I);
  }
  
  void Verifier::visitLoadInst(LoadInst &LI) {
    PointerType *PTy = dyn_cast<PointerType>(LI.getOperand(0)->getType());
    Assert(PTy, "Load operand must be a pointer.", &LI);
    Type *ElTy = LI.getType();
    Assert(LI.getAlignment() <= Value::MaximumAlignment,
           "huge alignment values are unsupported", &LI);
    Assert(ElTy->isSized(), "loading unsized types is not allowed", &LI);
    if (LI.isAtomic()) {
      Assert(LI.getOrdering() != AtomicOrdering::Release &&
                 LI.getOrdering() != AtomicOrdering::AcquireRelease,
             "Load cannot have Release ordering", &LI);
      Assert(LI.getAlignment() != 0,
             "Atomic load must specify explicit alignment", &LI);
      Assert(ElTy->isIntOrPtrTy() || ElTy->isFloatingPointTy(),
             "atomic load operand must have integer, pointer, or floating point "
             "type!",
             ElTy, &LI);
      checkAtomicMemAccessSize(ElTy, &LI);
    } else {
      Assert(LI.getSyncScopeID() == SyncScope::System,
             "Non-atomic load cannot have SynchronizationScope specified", &LI);
    }
  
    visitInstruction(LI);
  }
  
  void Verifier::visitStoreInst(StoreInst &SI) {
    PointerType *PTy = dyn_cast<PointerType>(SI.getOperand(1)->getType());
    Assert(PTy, "Store operand must be a pointer.", &SI);
    Type *ElTy = PTy->getElementType();
    Assert(ElTy == SI.getOperand(0)->getType(),
           "Stored value type does not match pointer operand type!", &SI, ElTy);
    Assert(SI.getAlignment() <= Value::MaximumAlignment,
           "huge alignment values are unsupported", &SI);
    Assert(ElTy->isSized(), "storing unsized types is not allowed", &SI);
    if (SI.isAtomic()) {
      Assert(SI.getOrdering() != AtomicOrdering::Acquire &&
                 SI.getOrdering() != AtomicOrdering::AcquireRelease,
             "Store cannot have Acquire ordering", &SI);
      Assert(SI.getAlignment() != 0,
             "Atomic store must specify explicit alignment", &SI);
      Assert(ElTy->isIntOrPtrTy() || ElTy->isFloatingPointTy(),
             "atomic store operand must have integer, pointer, or floating point "
             "type!",
             ElTy, &SI);
      checkAtomicMemAccessSize(ElTy, &SI);
    } else {
      Assert(SI.getSyncScopeID() == SyncScope::System,
             "Non-atomic store cannot have SynchronizationScope specified", &SI);
    }
    visitInstruction(SI);
  }
  
  /// Check that SwiftErrorVal is used as a swifterror argument in CS.
  void Verifier::verifySwiftErrorCall(CallBase &Call,
                                      const Value *SwiftErrorVal) {
    unsigned Idx = 0;
    for (auto I = Call.arg_begin(), E = Call.arg_end(); I != E; ++I, ++Idx) {
      if (*I == SwiftErrorVal) {
        Assert(Call.paramHasAttr(Idx, Attribute::SwiftError),
               "swifterror value when used in a callsite should be marked "
               "with swifterror attribute",
               SwiftErrorVal, Call);
      }
    }
  }
  
  void Verifier::verifySwiftErrorValue(const Value *SwiftErrorVal) {
    // Check that swifterror value is only used by loads, stores, or as
    // a swifterror argument.
    for (const User *U : SwiftErrorVal->users()) {
      Assert(isa<LoadInst>(U) || isa<StoreInst>(U) || isa<CallInst>(U) ||
             isa<InvokeInst>(U),
             "swifterror value can only be loaded and stored from, or "
             "as a swifterror argument!",
             SwiftErrorVal, U);
      // If it is used by a store, check it is the second operand.
      if (auto StoreI = dyn_cast<StoreInst>(U))
        Assert(StoreI->getOperand(1) == SwiftErrorVal,
               "swifterror value should be the second operand when used "
               "by stores", SwiftErrorVal, U);
      if (auto *Call = dyn_cast<CallBase>(U))
        verifySwiftErrorCall(*const_cast<CallBase *>(Call), SwiftErrorVal);
    }
  }
  
  void Verifier::visitAllocaInst(AllocaInst &AI) {
    SmallPtrSet<Type*, 4> Visited;
    PointerType *PTy = AI.getType();
    // TODO: Relax this restriction?
    Assert(PTy->getAddressSpace() == DL.getAllocaAddrSpace(),
           "Allocation instruction pointer not in the stack address space!",
           &AI);
    Assert(AI.getAllocatedType()->isSized(&Visited),
           "Cannot allocate unsized type", &AI);
    Assert(AI.getArraySize()->getType()->isIntegerTy(),
           "Alloca array size must have integer type", &AI);
    Assert(AI.getAlignment() <= Value::MaximumAlignment,
           "huge alignment values are unsupported", &AI);
  
    if (AI.isSwiftError()) {
      verifySwiftErrorValue(&AI);
    }
  
    visitInstruction(AI);
  }
  
  void Verifier::visitAtomicCmpXchgInst(AtomicCmpXchgInst &CXI) {
  
    // FIXME: more conditions???
    Assert(CXI.getSuccessOrdering() != AtomicOrdering::NotAtomic,
           "cmpxchg instructions must be atomic.", &CXI);
    Assert(CXI.getFailureOrdering() != AtomicOrdering::NotAtomic,
           "cmpxchg instructions must be atomic.", &CXI);
    Assert(CXI.getSuccessOrdering() != AtomicOrdering::Unordered,
           "cmpxchg instructions cannot be unordered.", &CXI);
    Assert(CXI.getFailureOrdering() != AtomicOrdering::Unordered,
           "cmpxchg instructions cannot be unordered.", &CXI);
    Assert(!isStrongerThan(CXI.getFailureOrdering(), CXI.getSuccessOrdering()),
           "cmpxchg instructions failure argument shall be no stronger than the "
           "success argument",
           &CXI);
    Assert(CXI.getFailureOrdering() != AtomicOrdering::Release &&
               CXI.getFailureOrdering() != AtomicOrdering::AcquireRelease,
           "cmpxchg failure ordering cannot include release semantics", &CXI);
  
    PointerType *PTy = dyn_cast<PointerType>(CXI.getOperand(0)->getType());
    Assert(PTy, "First cmpxchg operand must be a pointer.", &CXI);
    Type *ElTy = PTy->getElementType();
    Assert(ElTy->isIntOrPtrTy(),
           "cmpxchg operand must have integer or pointer type", ElTy, &CXI);
    checkAtomicMemAccessSize(ElTy, &CXI);
    Assert(ElTy == CXI.getOperand(1)->getType(),
           "Expected value type does not match pointer operand type!", &CXI,
           ElTy);
    Assert(ElTy == CXI.getOperand(2)->getType(),
           "Stored value type does not match pointer operand type!", &CXI, ElTy);
    visitInstruction(CXI);
  }
  
  void Verifier::visitAtomicRMWInst(AtomicRMWInst &RMWI) {
    Assert(RMWI.getOrdering() != AtomicOrdering::NotAtomic,
           "atomicrmw instructions must be atomic.", &RMWI);
    Assert(RMWI.getOrdering() != AtomicOrdering::Unordered,
           "atomicrmw instructions cannot be unordered.", &RMWI);
    auto Op = RMWI.getOperation();
    PointerType *PTy = dyn_cast<PointerType>(RMWI.getOperand(0)->getType());
    Assert(PTy, "First atomicrmw operand must be a pointer.", &RMWI);
    Type *ElTy = PTy->getElementType();
    if (Op == AtomicRMWInst::Xchg) {
      Assert(ElTy->isIntegerTy() || ElTy->isFloatingPointTy(), "atomicrmw " +
             AtomicRMWInst::getOperationName(Op) +
             " operand must have integer or floating point type!",
             &RMWI, ElTy);
    } else if (AtomicRMWInst::isFPOperation(Op)) {
      Assert(ElTy->isFloatingPointTy(), "atomicrmw " +
             AtomicRMWInst::getOperationName(Op) +
             " operand must have floating point type!",
             &RMWI, ElTy);
    } else {
      Assert(ElTy->isIntegerTy(), "atomicrmw " +
             AtomicRMWInst::getOperationName(Op) +
             " operand must have integer type!",
             &RMWI, ElTy);
    }
    checkAtomicMemAccessSize(ElTy, &RMWI);
    Assert(ElTy == RMWI.getOperand(1)->getType(),
           "Argument value type does not match pointer operand type!", &RMWI,
           ElTy);
    Assert(AtomicRMWInst::FIRST_BINOP <= Op && Op <= AtomicRMWInst::LAST_BINOP,
           "Invalid binary operation!", &RMWI);
    visitInstruction(RMWI);
  }
  
  void Verifier::visitFenceInst(FenceInst &FI) {
    const AtomicOrdering Ordering = FI.getOrdering();
    Assert(Ordering == AtomicOrdering::Acquire ||
               Ordering == AtomicOrdering::Release ||
               Ordering == AtomicOrdering::AcquireRelease ||
               Ordering == AtomicOrdering::SequentiallyConsistent,
           "fence instructions may only have acquire, release, acq_rel, or "
           "seq_cst ordering.",
           &FI);
    visitInstruction(FI);
  }
  
  void Verifier::visitExtractValueInst(ExtractValueInst &EVI) {
    Assert(ExtractValueInst::getIndexedType(EVI.getAggregateOperand()->getType(),
                                            EVI.getIndices()) == EVI.getType(),
           "Invalid ExtractValueInst operands!", &EVI);
  
    visitInstruction(EVI);
  }
  
  void Verifier::visitInsertValueInst(InsertValueInst &IVI) {
    Assert(ExtractValueInst::getIndexedType(IVI.getAggregateOperand()->getType(),
                                            IVI.getIndices()) ==
               IVI.getOperand(1)->getType(),
           "Invalid InsertValueInst operands!", &IVI);
  
    visitInstruction(IVI);
  }
  
  static Value *getParentPad(Value *EHPad) {
    if (auto *FPI = dyn_cast<FuncletPadInst>(EHPad))
      return FPI->getParentPad();
  
    return cast<CatchSwitchInst>(EHPad)->getParentPad();
  }
  
  void Verifier::visitEHPadPredecessors(Instruction &I) {
    assert(I.isEHPad());
  
    BasicBlock *BB = I.getParent();
    Function *F = BB->getParent();
  
    Assert(BB != &F->getEntryBlock(), "EH pad cannot be in entry block.", &I);
  
    if (auto *LPI = dyn_cast<LandingPadInst>(&I)) {
      // The landingpad instruction defines its parent as a landing pad block. The
      // landing pad block may be branched to only by the unwind edge of an
      // invoke.
      for (BasicBlock *PredBB : predecessors(BB)) {
        const auto *II = dyn_cast<InvokeInst>(PredBB->getTerminator());
        Assert(II && II->getUnwindDest() == BB && II->getNormalDest() != BB,
               "Block containing LandingPadInst must be jumped to "
               "only by the unwind edge of an invoke.",
               LPI);
      }
      return;
    }
    if (auto *CPI = dyn_cast<CatchPadInst>(&I)) {
      if (!pred_empty(BB))
        Assert(BB->getUniquePredecessor() == CPI->getCatchSwitch()->getParent(),
               "Block containg CatchPadInst must be jumped to "
               "only by its catchswitch.",
               CPI);
      Assert(BB != CPI->getCatchSwitch()->getUnwindDest(),
             "Catchswitch cannot unwind to one of its catchpads",
             CPI->getCatchSwitch(), CPI);
      return;
    }
  
    // Verify that each pred has a legal terminator with a legal to/from EH
    // pad relationship.
    Instruction *ToPad = &I;
    Value *ToPadParent = getParentPad(ToPad);
    for (BasicBlock *PredBB : predecessors(BB)) {
      Instruction *TI = PredBB->getTerminator();
      Value *FromPad;
      if (auto *II = dyn_cast<InvokeInst>(TI)) {
        Assert(II->getUnwindDest() == BB && II->getNormalDest() != BB,
               "EH pad must be jumped to via an unwind edge", ToPad, II);
        if (auto Bundle = II->getOperandBundle(LLVMContext::OB_funclet))
          FromPad = Bundle->Inputs[0];
        else
          FromPad = ConstantTokenNone::get(II->getContext());
      } else if (auto *CRI = dyn_cast<CleanupReturnInst>(TI)) {
        FromPad = CRI->getOperand(0);
        Assert(FromPad != ToPadParent, "A cleanupret must exit its cleanup", CRI);
      } else if (auto *CSI = dyn_cast<CatchSwitchInst>(TI)) {
        FromPad = CSI;
      } else {
        Assert(false, "EH pad must be jumped to via an unwind edge", ToPad, TI);
      }
  
      // The edge may exit from zero or more nested pads.
      SmallSet<Value *, 8> Seen;
      for (;; FromPad = getParentPad(FromPad)) {
        Assert(FromPad != ToPad,
               "EH pad cannot handle exceptions raised within it", FromPad, TI);
        if (FromPad == ToPadParent) {
          // This is a legal unwind edge.
          break;
        }
        Assert(!isa<ConstantTokenNone>(FromPad),
               "A single unwind edge may only enter one EH pad", TI);
        Assert(Seen.insert(FromPad).second,
               "EH pad jumps through a cycle of pads", FromPad);
      }
    }
  }
  
  void Verifier::visitLandingPadInst(LandingPadInst &LPI) {
    // The landingpad instruction is ill-formed if it doesn't have any clauses and
    // isn't a cleanup.
    Assert(LPI.getNumClauses() > 0 || LPI.isCleanup(),
           "LandingPadInst needs at least one clause or to be a cleanup.", &LPI);
  
    visitEHPadPredecessors(LPI);
  
    if (!LandingPadResultTy)
      LandingPadResultTy = LPI.getType();
    else
      Assert(LandingPadResultTy == LPI.getType(),
             "The landingpad instruction should have a consistent result type "
             "inside a function.",
             &LPI);
  
    Function *F = LPI.getParent()->getParent();
    Assert(F->hasPersonalityFn(),
           "LandingPadInst needs to be in a function with a personality.", &LPI);
  
    // The landingpad instruction must be the first non-PHI instruction in the
    // block.
    Assert(LPI.getParent()->getLandingPadInst() == &LPI,
           "LandingPadInst not the first non-PHI instruction in the block.",
           &LPI);
  
    for (unsigned i = 0, e = LPI.getNumClauses(); i < e; ++i) {
      Constant *Clause = LPI.getClause(i);
      if (LPI.isCatch(i)) {
        Assert(isa<PointerType>(Clause->getType()),
               "Catch operand does not have pointer type!", &LPI);
      } else {
        Assert(LPI.isFilter(i), "Clause is neither catch nor filter!", &LPI);
        Assert(isa<ConstantArray>(Clause) || isa<ConstantAggregateZero>(Clause),
               "Filter operand is not an array of constants!", &LPI);
      }
    }
  
    visitInstruction(LPI);
  }
  
  void Verifier::visitResumeInst(ResumeInst &RI) {
    Assert(RI.getFunction()->hasPersonalityFn(),
           "ResumeInst needs to be in a function with a personality.", &RI);
  
    if (!LandingPadResultTy)
      LandingPadResultTy = RI.getValue()->getType();
    else
      Assert(LandingPadResultTy == RI.getValue()->getType(),
             "The resume instruction should have a consistent result type "
             "inside a function.",
             &RI);
  
    visitTerminator(RI);
  }
  
  void Verifier::visitCatchPadInst(CatchPadInst &CPI) {
    BasicBlock *BB = CPI.getParent();
  
    Function *F = BB->getParent();
    Assert(F->hasPersonalityFn(),
           "CatchPadInst needs to be in a function with a personality.", &CPI);
  
    Assert(isa<CatchSwitchInst>(CPI.getParentPad()),
           "CatchPadInst needs to be directly nested in a CatchSwitchInst.",
           CPI.getParentPad());
  
    // The catchpad instruction must be the first non-PHI instruction in the
    // block.
    Assert(BB->getFirstNonPHI() == &CPI,
           "CatchPadInst not the first non-PHI instruction in the block.", &CPI);
  
    visitEHPadPredecessors(CPI);
    visitFuncletPadInst(CPI);
  }
  
  void Verifier::visitCatchReturnInst(CatchReturnInst &CatchReturn) {
    Assert(isa<CatchPadInst>(CatchReturn.getOperand(0)),
           "CatchReturnInst needs to be provided a CatchPad", &CatchReturn,
           CatchReturn.getOperand(0));
  
    visitTerminator(CatchReturn);
  }
  
  void Verifier::visitCleanupPadInst(CleanupPadInst &CPI) {
    BasicBlock *BB = CPI.getParent();
  
    Function *F = BB->getParent();
    Assert(F->hasPersonalityFn(),
           "CleanupPadInst needs to be in a function with a personality.", &CPI);
  
    // The cleanuppad instruction must be the first non-PHI instruction in the
    // block.
    Assert(BB->getFirstNonPHI() == &CPI,
           "CleanupPadInst not the first non-PHI instruction in the block.",
           &CPI);
  
    auto *ParentPad = CPI.getParentPad();
    Assert(isa<ConstantTokenNone>(ParentPad) || isa<FuncletPadInst>(ParentPad),
           "CleanupPadInst has an invalid parent.", &CPI);
  
    visitEHPadPredecessors(CPI);
    visitFuncletPadInst(CPI);
  }
  
  void Verifier::visitFuncletPadInst(FuncletPadInst &FPI) {
    User *FirstUser = nullptr;
    Value *FirstUnwindPad = nullptr;
    SmallVector<FuncletPadInst *, 8> Worklist({&FPI});
    SmallSet<FuncletPadInst *, 8> Seen;
  
    while (!Worklist.empty()) {
      FuncletPadInst *CurrentPad = Worklist.pop_back_val();
      Assert(Seen.insert(CurrentPad).second,
             "FuncletPadInst must not be nested within itself", CurrentPad);
      Value *UnresolvedAncestorPad = nullptr;
      for (User *U : CurrentPad->users()) {
        BasicBlock *UnwindDest;
        if (auto *CRI = dyn_cast<CleanupReturnInst>(U)) {
          UnwindDest = CRI->getUnwindDest();
        } else if (auto *CSI = dyn_cast<CatchSwitchInst>(U)) {
          // We allow catchswitch unwind to caller to nest
          // within an outer pad that unwinds somewhere else,
          // because catchswitch doesn't have a nounwind variant.
          // See e.g. SimplifyCFGOpt::SimplifyUnreachable.
          if (CSI->unwindsToCaller())
            continue;
          UnwindDest = CSI->getUnwindDest();
        } else if (auto *II = dyn_cast<InvokeInst>(U)) {
          UnwindDest = II->getUnwindDest();
        } else if (isa<CallInst>(U)) {
          // Calls which don't unwind may be found inside funclet
          // pads that unwind somewhere else.  We don't *require*
          // such calls to be annotated nounwind.
          continue;
        } else if (auto *CPI = dyn_cast<CleanupPadInst>(U)) {
          // The unwind dest for a cleanup can only be found by
          // recursive search.  Add it to the worklist, and we'll
          // search for its first use that determines where it unwinds.
          Worklist.push_back(CPI);
          continue;
        } else {
          Assert(isa<CatchReturnInst>(U), "Bogus funclet pad use", U);
          continue;
        }
  
        Value *UnwindPad;
        bool ExitsFPI;
        if (UnwindDest) {
          UnwindPad = UnwindDest->getFirstNonPHI();
          if (!cast<Instruction>(UnwindPad)->isEHPad())
            continue;
          Value *UnwindParent = getParentPad(UnwindPad);
          // Ignore unwind edges that don't exit CurrentPad.
          if (UnwindParent == CurrentPad)
            continue;
          // Determine whether the original funclet pad is exited,
          // and if we are scanning nested pads determine how many
          // of them are exited so we can stop searching their
          // children.
          Value *ExitedPad = CurrentPad;
          ExitsFPI = false;
          do {
            if (ExitedPad == &FPI) {
              ExitsFPI = true;
              // Now we can resolve any ancestors of CurrentPad up to
              // FPI, but not including FPI since we need to make sure
              // to check all direct users of FPI for consistency.
              UnresolvedAncestorPad = &FPI;
              break;
            }
            Value *ExitedParent = getParentPad(ExitedPad);
            if (ExitedParent == UnwindParent) {
              // ExitedPad is the ancestor-most pad which this unwind
              // edge exits, so we can resolve up to it, meaning that
              // ExitedParent is the first ancestor still unresolved.
              UnresolvedAncestorPad = ExitedParent;
              break;
            }
            ExitedPad = ExitedParent;
          } while (!isa<ConstantTokenNone>(ExitedPad));
        } else {
          // Unwinding to caller exits all pads.
          UnwindPad = ConstantTokenNone::get(FPI.getContext());
          ExitsFPI = true;
          UnresolvedAncestorPad = &FPI;
        }
  
        if (ExitsFPI) {
          // This unwind edge exits FPI.  Make sure it agrees with other
          // such edges.
          if (FirstUser) {
            Assert(UnwindPad == FirstUnwindPad, "Unwind edges out of a funclet "
                                                "pad must have the same unwind "
                                                "dest",
                   &FPI, U, FirstUser);
          } else {
            FirstUser = U;
            FirstUnwindPad = UnwindPad;
            // Record cleanup sibling unwinds for verifySiblingFuncletUnwinds
            if (isa<CleanupPadInst>(&FPI) && !isa<ConstantTokenNone>(UnwindPad) &&
                getParentPad(UnwindPad) == getParentPad(&FPI))
              SiblingFuncletInfo[&FPI] = cast<Instruction>(U);
          }
        }
        // Make sure we visit all uses of FPI, but for nested pads stop as
        // soon as we know where they unwind to.
        if (CurrentPad != &FPI)
          break;
      }
      if (UnresolvedAncestorPad) {
        if (CurrentPad == UnresolvedAncestorPad) {
          // When CurrentPad is FPI itself, we don't mark it as resolved even if
          // we've found an unwind edge that exits it, because we need to verify
          // all direct uses of FPI.
          assert(CurrentPad == &FPI);
          continue;
        }
        // Pop off the worklist any nested pads that we've found an unwind
        // destination for.  The pads on the worklist are the uncles,
        // great-uncles, etc. of CurrentPad.  We've found an unwind destination
        // for all ancestors of CurrentPad up to but not including
        // UnresolvedAncestorPad.
        Value *ResolvedPad = CurrentPad;
        while (!Worklist.empty()) {
          Value *UnclePad = Worklist.back();
          Value *AncestorPad = getParentPad(UnclePad);
          // Walk ResolvedPad up the ancestor list until we either find the
          // uncle's parent or the last resolved ancestor.
          while (ResolvedPad != AncestorPad) {
            Value *ResolvedParent = getParentPad(ResolvedPad);
            if (ResolvedParent == UnresolvedAncestorPad) {
              break;
            }
            ResolvedPad = ResolvedParent;
          }
          // If the resolved ancestor search didn't find the uncle's parent,
          // then the uncle is not yet resolved.
          if (ResolvedPad != AncestorPad)
            break;
          // This uncle is resolved, so pop it from the worklist.
          Worklist.pop_back();
        }
      }
    }
  
    if (FirstUnwindPad) {
      if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(FPI.getParentPad())) {
        BasicBlock *SwitchUnwindDest = CatchSwitch->getUnwindDest();
        Value *SwitchUnwindPad;
        if (SwitchUnwindDest)
          SwitchUnwindPad = SwitchUnwindDest->getFirstNonPHI();
        else
          SwitchUnwindPad = ConstantTokenNone::get(FPI.getContext());
        Assert(SwitchUnwindPad == FirstUnwindPad,
               "Unwind edges out of a catch must have the same unwind dest as "
               "the parent catchswitch",
               &FPI, FirstUser, CatchSwitch);
      }
    }
  
    visitInstruction(FPI);
  }
  
  void Verifier::visitCatchSwitchInst(CatchSwitchInst &CatchSwitch) {
    BasicBlock *BB = CatchSwitch.getParent();
  
    Function *F = BB->getParent();
    Assert(F->hasPersonalityFn(),
           "CatchSwitchInst needs to be in a function with a personality.",
           &CatchSwitch);
  
    // The catchswitch instruction must be the first non-PHI instruction in the
    // block.
    Assert(BB->getFirstNonPHI() == &CatchSwitch,
           "CatchSwitchInst not the first non-PHI instruction in the block.",
           &CatchSwitch);
  
    auto *ParentPad = CatchSwitch.getParentPad();
    Assert(isa<ConstantTokenNone>(ParentPad) || isa<FuncletPadInst>(ParentPad),
           "CatchSwitchInst has an invalid parent.", ParentPad);
  
    if (BasicBlock *UnwindDest = CatchSwitch.getUnwindDest()) {
      Instruction *I = UnwindDest->getFirstNonPHI();
      Assert(I->isEHPad() && !isa<LandingPadInst>(I),
             "CatchSwitchInst must unwind to an EH block which is not a "
             "landingpad.",
             &CatchSwitch);
  
      // Record catchswitch sibling unwinds for verifySiblingFuncletUnwinds
      if (getParentPad(I) == ParentPad)
        SiblingFuncletInfo[&CatchSwitch] = &CatchSwitch;
    }
  
    Assert(CatchSwitch.getNumHandlers() != 0,
           "CatchSwitchInst cannot have empty handler list", &CatchSwitch);
  
    for (BasicBlock *Handler : CatchSwitch.handlers()) {
      Assert(isa<CatchPadInst>(Handler->getFirstNonPHI()),
             "CatchSwitchInst handlers must be catchpads", &CatchSwitch, Handler);
    }
  
    visitEHPadPredecessors(CatchSwitch);
    visitTerminator(CatchSwitch);
  }
  
  void Verifier::visitCleanupReturnInst(CleanupReturnInst &CRI) {
    Assert(isa<CleanupPadInst>(CRI.getOperand(0)),
           "CleanupReturnInst needs to be provided a CleanupPad", &CRI,
           CRI.getOperand(0));
  
    if (BasicBlock *UnwindDest = CRI.getUnwindDest()) {
      Instruction *I = UnwindDest->getFirstNonPHI();
      Assert(I->isEHPad() && !isa<LandingPadInst>(I),
             "CleanupReturnInst must unwind to an EH block which is not a "
             "landingpad.",
             &CRI);
    }
  
    visitTerminator(CRI);
  }
  
  void Verifier::verifyDominatesUse(Instruction &I, unsigned i) {
    Instruction *Op = cast<Instruction>(I.getOperand(i));
    // If the we have an invalid invoke, don't try to compute the dominance.
    // We already reject it in the invoke specific checks and the dominance
    // computation doesn't handle multiple edges.
    if (InvokeInst *II = dyn_cast<InvokeInst>(Op)) {
      if (II->getNormalDest() == II->getUnwindDest())
        return;
    }
  
    // Quick check whether the def has already been encountered in the same block.
    // PHI nodes are not checked to prevent accepting preceding PHIs, because PHI
    // uses are defined to happen on the incoming edge, not at the instruction.
    //
    // FIXME: If this operand is a MetadataAsValue (wrapping a LocalAsMetadata)
    // wrapping an SSA value, assert that we've already encountered it.  See
    // related FIXME in Mapper::mapLocalAsMetadata in ValueMapper.cpp.
    if (!isa<PHINode>(I) && InstsInThisBlock.count(Op))
      return;
  
    const Use &U = I.getOperandUse(i);
    Assert(DT.dominates(Op, U),
           "Instruction does not dominate all uses!", Op, &I);
  }
  
  void Verifier::visitDereferenceableMetadata(Instruction& I, MDNode* MD) {
    Assert(I.getType()->isPointerTy(), "dereferenceable, dereferenceable_or_null "
           "apply only to pointer types", &I);
    Assert(isa<LoadInst>(I),
           "dereferenceable, dereferenceable_or_null apply only to load"
           " instructions, use attributes for calls or invokes", &I);
    Assert(MD->getNumOperands() == 1, "dereferenceable, dereferenceable_or_null "
           "take one operand!", &I);
    ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(MD->getOperand(0));
    Assert(CI && CI->getType()->isIntegerTy(64), "dereferenceable, "
           "dereferenceable_or_null metadata value must be an i64!", &I);
  }
  
  /// verifyInstruction - Verify that an instruction is well formed.
  ///
  void Verifier::visitInstruction(Instruction &I) {
    BasicBlock *BB = I.getParent();
    Assert(BB, "Instruction not embedded in basic block!", &I);
  
    if (!isa<PHINode>(I)) {   // Check that non-phi nodes are not self referential
      for (User *U : I.users()) {
        Assert(U != (User *)&I || !DT.isReachableFromEntry(BB),
               "Only PHI nodes may reference their own value!", &I);
      }
    }
  
    // Check that void typed values don't have names
    Assert(!I.getType()->isVoidTy() || !I.hasName(),
           "Instruction has a name, but provides a void value!", &I);
  
    // Check that the return value of the instruction is either void or a legal
    // value type.
    Assert(I.getType()->isVoidTy() || I.getType()->isFirstClassType(),
           "Instruction returns a non-scalar type!", &I);
  
    // Check that the instruction doesn't produce metadata. Calls are already
    // checked against the callee type.
    Assert(!I.getType()->isMetadataTy() || isa<CallInst>(I) || isa<InvokeInst>(I),
           "Invalid use of metadata!", &I);
  
    // Check that all uses of the instruction, if they are instructions
    // themselves, actually have parent basic blocks.  If the use is not an
    // instruction, it is an error!
    for (Use &U : I.uses()) {
      if (Instruction *Used = dyn_cast<Instruction>(U.getUser()))
        Assert(Used->getParent() != nullptr,
               "Instruction referencing"
               " instruction not embedded in a basic block!",
               &I, Used);
      else {
        CheckFailed("Use of instruction is not an instruction!", U);
        return;
      }
    }
  
    // Get a pointer to the call base of the instruction if it is some form of
    // call.
    const CallBase *CBI = dyn_cast<CallBase>(&I);
  
    for (unsigned i = 0, e = I.getNumOperands(); i != e; ++i) {
      Assert(I.getOperand(i) != nullptr, "Instruction has null operand!", &I);
  
      // Check to make sure that only first-class-values are operands to
      // instructions.
      if (!I.getOperand(i)->getType()->isFirstClassType()) {
        Assert(false, "Instruction operands must be first-class values!", &I);
      }
  
      if (Function *F = dyn_cast<Function>(I.getOperand(i))) {
        // Check to make sure that the "address of" an intrinsic function is never
        // taken.
        Assert(!F->isIntrinsic() ||
                   (CBI && &CBI->getCalledOperandUse() == &I.getOperandUse(i)),
               "Cannot take the address of an intrinsic!", &I);
        Assert(
            !F->isIntrinsic() || isa<CallInst>(I) ||
                F->getIntrinsicID() == Intrinsic::donothing ||
                F->getIntrinsicID() == Intrinsic::coro_resume ||
                F->getIntrinsicID() == Intrinsic::coro_destroy ||
                F->getIntrinsicID() == Intrinsic::experimental_patchpoint_void ||
                F->getIntrinsicID() == Intrinsic::experimental_patchpoint_i64 ||
                F->getIntrinsicID() == Intrinsic::experimental_gc_statepoint ||
                F->getIntrinsicID() == Intrinsic::wasm_rethrow_in_catch,
            "Cannot invoke an intrinsic other than donothing, patchpoint, "
            "statepoint, coro_resume or coro_destroy",
            &I);
        Assert(F->getParent() == &M, "Referencing function in another module!",
               &I, &M, F, F->getParent());
      } else if (BasicBlock *OpBB = dyn_cast<BasicBlock>(I.getOperand(i))) {
        Assert(OpBB->getParent() == BB->getParent(),
               "Referring to a basic block in another function!", &I);
      } else if (Argument *OpArg = dyn_cast<Argument>(I.getOperand(i))) {
        Assert(OpArg->getParent() == BB->getParent(),
               "Referring to an argument in another function!", &I);
      } else if (GlobalValue *GV = dyn_cast<GlobalValue>(I.getOperand(i))) {
        Assert(GV->getParent() == &M, "Referencing global in another module!", &I,
               &M, GV, GV->getParent());
      } else if (isa<Instruction>(I.getOperand(i))) {
        verifyDominatesUse(I, i);
      } else if (isa<InlineAsm>(I.getOperand(i))) {
        Assert(CBI && &CBI->getCalledOperandUse() == &I.getOperandUse(i),
               "Cannot take the address of an inline asm!", &I);
      } else if (ConstantExpr *CE = dyn_cast<ConstantExpr>(I.getOperand(i))) {
        if (CE->getType()->isPtrOrPtrVectorTy() ||
            !DL.getNonIntegralAddressSpaces().empty()) {
          // If we have a ConstantExpr pointer, we need to see if it came from an
          // illegal bitcast.  If the datalayout string specifies non-integral
          // address spaces then we also need to check for illegal ptrtoint and
          // inttoptr expressions.
          visitConstantExprsRecursively(CE);
        }
      }
    }
  
    if (MDNode *MD = I.getMetadata(LLVMContext::MD_fpmath)) {
      Assert(I.getType()->isFPOrFPVectorTy(),
             "fpmath requires a floating point result!", &I);
      Assert(MD->getNumOperands() == 1, "fpmath takes one operand!", &I);
      if (ConstantFP *CFP0 =
              mdconst::dyn_extract_or_null<ConstantFP>(MD->getOperand(0))) {
        const APFloat &Accuracy = CFP0->getValueAPF();
        Assert(&Accuracy.getSemantics() == &APFloat::IEEEsingle(),
               "fpmath accuracy must have float type", &I);
        Assert(Accuracy.isFiniteNonZero() && !Accuracy.isNegative(),
               "fpmath accuracy not a positive number!", &I);
      } else {
        Assert(false, "invalid fpmath accuracy!", &I);
      }
    }
  
    if (MDNode *Range = I.getMetadata(LLVMContext::MD_range)) {
      Assert(isa<LoadInst>(I) || isa<CallInst>(I) || isa<InvokeInst>(I),
             "Ranges are only for loads, calls and invokes!", &I);
      visitRangeMetadata(I, Range, I.getType());
    }
  
    if (I.getMetadata(LLVMContext::MD_nonnull)) {
      Assert(I.getType()->isPointerTy(), "nonnull applies only to pointer types",
             &I);
      Assert(isa<LoadInst>(I),
             "nonnull applies only to load instructions, use attributes"
             " for calls or invokes",
             &I);
    }
  
    if (MDNode *MD = I.getMetadata(LLVMContext::MD_dereferenceable))
      visitDereferenceableMetadata(I, MD);
  
    if (MDNode *MD = I.getMetadata(LLVMContext::MD_dereferenceable_or_null))
      visitDereferenceableMetadata(I, MD);
  
    if (MDNode *TBAA = I.getMetadata(LLVMContext::MD_tbaa))
      TBAAVerifyHelper.visitTBAAMetadata(I, TBAA);
  
    if (MDNode *AlignMD = I.getMetadata(LLVMContext::MD_align)) {
      Assert(I.getType()->isPointerTy(), "align applies only to pointer types",
             &I);
      Assert(isa<LoadInst>(I), "align applies only to load instructions, "
             "use attributes for calls or invokes", &I);
      Assert(AlignMD->getNumOperands() == 1, "align takes one operand!", &I);
      ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(AlignMD->getOperand(0));
      Assert(CI && CI->getType()->isIntegerTy(64),
             "align metadata value must be an i64!", &I);
      uint64_t Align = CI->getZExtValue();
      Assert(isPowerOf2_64(Align),
             "align metadata value must be a power of 2!", &I);
      Assert(Align <= Value::MaximumAlignment,
             "alignment is larger that implementation defined limit", &I);
    }
  
    if (MDNode *N = I.getDebugLoc().getAsMDNode()) {
      AssertDI(isa<DILocation>(N), "invalid !dbg metadata attachment", &I, N);
      visitMDNode(*N);
    }
  
    if (auto *DII = dyn_cast<DbgVariableIntrinsic>(&I))
      verifyFragmentExpression(*DII);
  
    InstsInThisBlock.insert(&I);
  }
  
  /// Allow intrinsics to be verified in different ways.
  void Verifier::visitIntrinsicCall(Intrinsic::ID ID, CallBase &Call) {
    Function *IF = Call.getCalledFunction();
    Assert(IF->isDeclaration(), "Intrinsic functions should never be defined!",
           IF);
  
    // Verify that the intrinsic prototype lines up with what the .td files
    // describe.
    FunctionType *IFTy = IF->getFunctionType();
    bool IsVarArg = IFTy->isVarArg();
  
    SmallVector<Intrinsic::IITDescriptor, 8> Table;
    getIntrinsicInfoTableEntries(ID, Table);
    ArrayRef<Intrinsic::IITDescriptor> TableRef = Table;
  
    // Walk the descriptors to extract overloaded types.
    SmallVector<Type *, 4> ArgTys;
    Intrinsic::MatchIntrinsicTypesResult Res =
        Intrinsic::matchIntrinsicSignature(IFTy, TableRef, ArgTys);
    Assert(Res != Intrinsic::MatchIntrinsicTypes_NoMatchRet,
           "Intrinsic has incorrect return type!", IF);
    Assert(Res != Intrinsic::MatchIntrinsicTypes_NoMatchArg,
           "Intrinsic has incorrect argument type!", IF);
  
    // Verify if the intrinsic call matches the vararg property.
    if (IsVarArg)
      Assert(!Intrinsic::matchIntrinsicVarArg(IsVarArg, TableRef),
             "Intrinsic was not defined with variable arguments!", IF);
    else
      Assert(!Intrinsic::matchIntrinsicVarArg(IsVarArg, TableRef),
             "Callsite was not defined with variable arguments!", IF);
  
    // All descriptors should be absorbed by now.
    Assert(TableRef.empty(), "Intrinsic has too few arguments!", IF);
  
    // Now that we have the intrinsic ID and the actual argument types (and we
    // know they are legal for the intrinsic!) get the intrinsic name through the
    // usual means.  This allows us to verify the mangling of argument types into
    // the name.
    const std::string ExpectedName = Intrinsic::getName(ID, ArgTys);
    Assert(ExpectedName == IF->getName(),
           "Intrinsic name not mangled correctly for type arguments! "
           "Should be: " +
               ExpectedName,
           IF);
  
    // If the intrinsic takes MDNode arguments, verify that they are either global
    // or are local to *this* function.
    for (Value *V : Call.args())
      if (auto *MD = dyn_cast<MetadataAsValue>(V))
        visitMetadataAsValue(*MD, Call.getCaller());
  
    switch (ID) {
    default:
      break;
    case Intrinsic::coro_id: {
      auto *InfoArg = Call.getArgOperand(3)->stripPointerCasts();
      if (isa<ConstantPointerNull>(InfoArg))
        break;
      auto *GV = dyn_cast<GlobalVariable>(InfoArg);
      Assert(GV && GV->isConstant() && GV->hasDefinitiveInitializer(),
        "info argument of llvm.coro.begin must refer to an initialized "
        "constant");
      Constant *Init = GV->getInitializer();
      Assert(isa<ConstantStruct>(Init) || isa<ConstantArray>(Init),
        "info argument of llvm.coro.begin must refer to either a struct or "
        "an array");
      break;
    }
    case Intrinsic::experimental_constrained_fadd:
    case Intrinsic::experimental_constrained_fsub:
    case Intrinsic::experimental_constrained_fmul:
    case Intrinsic::experimental_constrained_fdiv:
    case Intrinsic::experimental_constrained_frem:
    case Intrinsic::experimental_constrained_fma:
    case Intrinsic::experimental_constrained_fptrunc:
    case Intrinsic::experimental_constrained_fpext:
    case Intrinsic::experimental_constrained_sqrt:
    case Intrinsic::experimental_constrained_pow:
    case Intrinsic::experimental_constrained_powi:
    case Intrinsic::experimental_constrained_sin:
    case Intrinsic::experimental_constrained_cos:
    case Intrinsic::experimental_constrained_exp:
    case Intrinsic::experimental_constrained_exp2:
    case Intrinsic::experimental_constrained_log:
    case Intrinsic::experimental_constrained_log10:
    case Intrinsic::experimental_constrained_log2:
    case Intrinsic::experimental_constrained_rint:
    case Intrinsic::experimental_constrained_nearbyint:
    case Intrinsic::experimental_constrained_maxnum:
    case Intrinsic::experimental_constrained_minnum:
    case Intrinsic::experimental_constrained_ceil:
    case Intrinsic::experimental_constrained_floor:
    case Intrinsic::experimental_constrained_round:
    case Intrinsic::experimental_constrained_trunc:
      visitConstrainedFPIntrinsic(cast<ConstrainedFPIntrinsic>(Call));
      break;
    case Intrinsic::dbg_declare: // llvm.dbg.declare
      Assert(isa<MetadataAsValue>(Call.getArgOperand(0)),
             "invalid llvm.dbg.declare intrinsic call 1", Call);
      visitDbgIntrinsic("declare", cast<DbgVariableIntrinsic>(Call));
      break;
    case Intrinsic::dbg_addr: // llvm.dbg.addr
      visitDbgIntrinsic("addr", cast<DbgVariableIntrinsic>(Call));
      break;
    case Intrinsic::dbg_value: // llvm.dbg.value
      visitDbgIntrinsic("value", cast<DbgVariableIntrinsic>(Call));
      break;
    case Intrinsic::dbg_label: // llvm.dbg.label
      visitDbgLabelIntrinsic("label", cast<DbgLabelInst>(Call));
      break;
    case Intrinsic::memcpy:
    case Intrinsic::memmove:
    case Intrinsic::memset: {
      const auto *MI = cast<MemIntrinsic>(&Call);
      auto IsValidAlignment = [&](unsigned Alignment) -> bool {
        return Alignment == 0 || isPowerOf2_32(Alignment);
      };
      Assert(IsValidAlignment(MI->getDestAlignment()),
             "alignment of arg 0 of memory intrinsic must be 0 or a power of 2",
             Call);
      if (const auto *MTI = dyn_cast<MemTransferInst>(MI)) {
        Assert(IsValidAlignment(MTI->getSourceAlignment()),
               "alignment of arg 1 of memory intrinsic must be 0 or a power of 2",
               Call);
      }
  
      break;
    }
    case Intrinsic::memcpy_element_unordered_atomic:
    case Intrinsic::memmove_element_unordered_atomic:
    case Intrinsic::memset_element_unordered_atomic: {
      const auto *AMI = cast<AtomicMemIntrinsic>(&Call);
  
      ConstantInt *ElementSizeCI =
          cast<ConstantInt>(AMI->getRawElementSizeInBytes());
      const APInt &ElementSizeVal = ElementSizeCI->getValue();
      Assert(ElementSizeVal.isPowerOf2(),
             "element size of the element-wise atomic memory intrinsic "
             "must be a power of 2",
             Call);
  
      if (auto *LengthCI = dyn_cast<ConstantInt>(AMI->getLength())) {
        uint64_t Length = LengthCI->getZExtValue();
        uint64_t ElementSize = AMI->getElementSizeInBytes();
        Assert((Length % ElementSize) == 0,
               "constant length must be a multiple of the element size in the "
               "element-wise atomic memory intrinsic",
               Call);
      }
  
      auto IsValidAlignment = [&](uint64_t Alignment) {
        return isPowerOf2_64(Alignment) && ElementSizeVal.ule(Alignment);
      };
      uint64_t DstAlignment = AMI->getDestAlignment();
      Assert(IsValidAlignment(DstAlignment),
             "incorrect alignment of the destination argument", Call);
      if (const auto *AMT = dyn_cast<AtomicMemTransferInst>(AMI)) {
        uint64_t SrcAlignment = AMT->getSourceAlignment();
        Assert(IsValidAlignment(SrcAlignment),
               "incorrect alignment of the source argument", Call);
      }
      break;
    }
    case Intrinsic::gcroot:
    case Intrinsic::gcwrite:
    case Intrinsic::gcread:
      if (ID == Intrinsic::gcroot) {
        AllocaInst *AI =
            dyn_cast<AllocaInst>(Call.getArgOperand(0)->stripPointerCasts());
        Assert(AI, "llvm.gcroot parameter #1 must be an alloca.", Call);
        Assert(isa<Constant>(Call.getArgOperand(1)),
               "llvm.gcroot parameter #2 must be a constant.", Call);
        if (!AI->getAllocatedType()->isPointerTy()) {
          Assert(!isa<ConstantPointerNull>(Call.getArgOperand(1)),
                 "llvm.gcroot parameter #1 must either be a pointer alloca, "
                 "or argument #2 must be a non-null constant.",
                 Call);
        }
      }
  
      Assert(Call.getParent()->getParent()->hasGC(),
             "Enclosing function does not use GC.", Call);
      break;
    case Intrinsic::init_trampoline:
      Assert(isa<Function>(Call.getArgOperand(1)->stripPointerCasts()),
             "llvm.init_trampoline parameter #2 must resolve to a function.",
             Call);
      break;
    case Intrinsic::prefetch:
      Assert(cast<ConstantInt>(Call.getArgOperand(1))->getZExtValue() < 2 &&
             cast<ConstantInt>(Call.getArgOperand(2))->getZExtValue() < 4,
             "invalid arguments to llvm.prefetch", Call);
      break;
    case Intrinsic::stackprotector:
      Assert(isa<AllocaInst>(Call.getArgOperand(1)->stripPointerCasts()),
             "llvm.stackprotector parameter #2 must resolve to an alloca.", Call);
      break;
    case Intrinsic::localescape: {
      BasicBlock *BB = Call.getParent();
      Assert(BB == &BB->getParent()->front(),
             "llvm.localescape used outside of entry block", Call);
      Assert(!SawFrameEscape,
             "multiple calls to llvm.localescape in one function", Call);
      for (Value *Arg : Call.args()) {
        if (isa<ConstantPointerNull>(Arg))
          continue; // Null values are allowed as placeholders.
        auto *AI = dyn_cast<AllocaInst>(Arg->stripPointerCasts());
        Assert(AI && AI->isStaticAlloca(),
               "llvm.localescape only accepts static allocas", Call);
      }
      FrameEscapeInfo[BB->getParent()].first = Call.getNumArgOperands();
      SawFrameEscape = true;
      break;
    }
    case Intrinsic::localrecover: {
      Value *FnArg = Call.getArgOperand(0)->stripPointerCasts();
      Function *Fn = dyn_cast<Function>(FnArg);
      Assert(Fn && !Fn->isDeclaration(),
             "llvm.localrecover first "
             "argument must be function defined in this module",
             Call);
      auto *IdxArg = cast<ConstantInt>(Call.getArgOperand(2));
      auto &Entry = FrameEscapeInfo[Fn];
      Entry.second = unsigned(
          std::max(uint64_t(Entry.second), IdxArg->getLimitedValue(~0U) + 1));
      break;
    }
  
    case Intrinsic::experimental_gc_statepoint:
      if (auto *CI = dyn_cast<CallInst>(&Call))
        Assert(!CI->isInlineAsm(),
               "gc.statepoint support for inline assembly unimplemented", CI);
      Assert(Call.getParent()->getParent()->hasGC(),
             "Enclosing function does not use GC.", Call);
  
      verifyStatepoint(Call);
      break;
    case Intrinsic::experimental_gc_result: {
      Assert(Call.getParent()->getParent()->hasGC(),
             "Enclosing function does not use GC.", Call);
      // Are we tied to a statepoint properly?
      const auto *StatepointCall = dyn_cast<CallBase>(Call.getArgOperand(0));
      const Function *StatepointFn =
          StatepointCall ? StatepointCall->getCalledFunction() : nullptr;
      Assert(StatepointFn && StatepointFn->isDeclaration() &&
                 StatepointFn->getIntrinsicID() ==
                     Intrinsic::experimental_gc_statepoint,
             "gc.result operand #1 must be from a statepoint", Call,
             Call.getArgOperand(0));
  
      // Assert that result type matches wrapped callee.
      const Value *Target = StatepointCall->getArgOperand(2);
      auto *PT = cast<PointerType>(Target->getType());
      auto *TargetFuncType = cast<FunctionType>(PT->getElementType());
      Assert(Call.getType() == TargetFuncType->getReturnType(),
             "gc.result result type does not match wrapped callee", Call);
      break;
    }
    case Intrinsic::experimental_gc_relocate: {
      Assert(Call.getNumArgOperands() == 3, "wrong number of arguments", Call);
  
      Assert(isa<PointerType>(Call.getType()->getScalarType()),
             "gc.relocate must return a pointer or a vector of pointers", Call);
  
      // Check that this relocate is correctly tied to the statepoint
  
      // This is case for relocate on the unwinding path of an invoke statepoint
      if (LandingPadInst *LandingPad =
              dyn_cast<LandingPadInst>(Call.getArgOperand(0))) {
  
        const BasicBlock *InvokeBB =
            LandingPad->getParent()->getUniquePredecessor();
  
        // Landingpad relocates should have only one predecessor with invoke
        // statepoint terminator
        Assert(InvokeBB, "safepoints should have unique landingpads",
               LandingPad->getParent());
        Assert(InvokeBB->getTerminator(), "safepoint block should be well formed",
               InvokeBB);
        Assert(isStatepoint(InvokeBB->getTerminator()),
               "gc relocate should be linked to a statepoint", InvokeBB);
      } else {
        // In all other cases relocate should be tied to the statepoint directly.
        // This covers relocates on a normal return path of invoke statepoint and
        // relocates of a call statepoint.
        auto Token = Call.getArgOperand(0);
        Assert(isa<Instruction>(Token) && isStatepoint(cast<Instruction>(Token)),
               "gc relocate is incorrectly tied to the statepoint", Call, Token);
      }
  
      // Verify rest of the relocate arguments.
      const CallBase &StatepointCall =
          *cast<CallBase>(cast<GCRelocateInst>(Call).getStatepoint());
  
      // Both the base and derived must be piped through the safepoint.
      Value *Base = Call.getArgOperand(1);
      Assert(isa<ConstantInt>(Base),
             "gc.relocate operand #2 must be integer offset", Call);
  
      Value *Derived = Call.getArgOperand(2);
      Assert(isa<ConstantInt>(Derived),
             "gc.relocate operand #3 must be integer offset", Call);
  
      const int BaseIndex = cast<ConstantInt>(Base)->getZExtValue();
      const int DerivedIndex = cast<ConstantInt>(Derived)->getZExtValue();
      // Check the bounds
      Assert(0 <= BaseIndex && BaseIndex < (int)StatepointCall.arg_size(),
             "gc.relocate: statepoint base index out of bounds", Call);
      Assert(0 <= DerivedIndex && DerivedIndex < (int)StatepointCall.arg_size(),
             "gc.relocate: statepoint derived index out of bounds", Call);
  
      // Check that BaseIndex and DerivedIndex fall within the 'gc parameters'
      // section of the statepoint's argument.
      Assert(StatepointCall.arg_size() > 0,
             "gc.statepoint: insufficient arguments");
      Assert(isa<ConstantInt>(StatepointCall.getArgOperand(3)),
             "gc.statement: number of call arguments must be constant integer");
      const unsigned NumCallArgs =
          cast<ConstantInt>(StatepointCall.getArgOperand(3))->getZExtValue();
      Assert(StatepointCall.arg_size() > NumCallArgs + 5,
             "gc.statepoint: mismatch in number of call arguments");
      Assert(isa<ConstantInt>(StatepointCall.getArgOperand(NumCallArgs + 5)),
             "gc.statepoint: number of transition arguments must be "
             "a constant integer");
      const int NumTransitionArgs =
          cast<ConstantInt>(StatepointCall.getArgOperand(NumCallArgs + 5))
              ->getZExtValue();
      const int DeoptArgsStart = 4 + NumCallArgs + 1 + NumTransitionArgs + 1;
      Assert(isa<ConstantInt>(StatepointCall.getArgOperand(DeoptArgsStart)),
             "gc.statepoint: number of deoptimization arguments must be "
             "a constant integer");
      const int NumDeoptArgs =
          cast<ConstantInt>(StatepointCall.getArgOperand(DeoptArgsStart))
              ->getZExtValue();
      const int GCParamArgsStart = DeoptArgsStart + 1 + NumDeoptArgs;
      const int GCParamArgsEnd = StatepointCall.arg_size();
      Assert(GCParamArgsStart <= BaseIndex && BaseIndex < GCParamArgsEnd,
             "gc.relocate: statepoint base index doesn't fall within the "
             "'gc parameters' section of the statepoint call",
             Call);
      Assert(GCParamArgsStart <= DerivedIndex && DerivedIndex < GCParamArgsEnd,
             "gc.relocate: statepoint derived index doesn't fall within the "
             "'gc parameters' section of the statepoint call",
             Call);
  
      // Relocated value must be either a pointer type or vector-of-pointer type,
      // but gc_relocate does not need to return the same pointer type as the
      // relocated pointer. It can be casted to the correct type later if it's
      // desired. However, they must have the same address space and 'vectorness'
      GCRelocateInst &Relocate = cast<GCRelocateInst>(Call);
      Assert(Relocate.getDerivedPtr()->getType()->isPtrOrPtrVectorTy(),
             "gc.relocate: relocated value must be a gc pointer", Call);
  
      auto ResultType = Call.getType();
      auto DerivedType = Relocate.getDerivedPtr()->getType();
      Assert(ResultType->isVectorTy() == DerivedType->isVectorTy(),
             "gc.relocate: vector relocates to vector and pointer to pointer",
             Call);
      Assert(
          ResultType->getPointerAddressSpace() ==
              DerivedType->getPointerAddressSpace(),
          "gc.relocate: relocating a pointer shouldn't change its address space",
          Call);
      break;
    }
    case Intrinsic::eh_exceptioncode:
    case Intrinsic::eh_exceptionpointer: {
      Assert(isa<CatchPadInst>(Call.getArgOperand(0)),
             "eh.exceptionpointer argument must be a catchpad", Call);
      break;
    }
    case Intrinsic::masked_load: {
      Assert(Call.getType()->isVectorTy(), "masked_load: must return a vector",
             Call);
  
      Value *Ptr = Call.getArgOperand(0);
      ConstantInt *Alignment = cast<ConstantInt>(Call.getArgOperand(1));
      Value *Mask = Call.getArgOperand(2);
      Value *PassThru = Call.getArgOperand(3);
      Assert(Mask->getType()->isVectorTy(), "masked_load: mask must be vector",
             Call);
      Assert(Alignment->getValue().isPowerOf2(),
             "masked_load: alignment must be a power of 2", Call);
  
      // DataTy is the overloaded type
      Type *DataTy = cast<PointerType>(Ptr->getType())->getElementType();
      Assert(DataTy == Call.getType(),
             "masked_load: return must match pointer type", Call);
      Assert(PassThru->getType() == DataTy,
             "masked_load: pass through and data type must match", Call);
      Assert(Mask->getType()->getVectorNumElements() ==
                 DataTy->getVectorNumElements(),
             "masked_load: vector mask must be same length as data", Call);
      break;
    }
    case Intrinsic::masked_store: {
      Value *Val = Call.getArgOperand(0);
      Value *Ptr = Call.getArgOperand(1);
      ConstantInt *Alignment = cast<ConstantInt>(Call.getArgOperand(2));
      Value *Mask = Call.getArgOperand(3);
      Assert(Mask->getType()->isVectorTy(), "masked_store: mask must be vector",
             Call);
      Assert(Alignment->getValue().isPowerOf2(),
             "masked_store: alignment must be a power of 2", Call);
  
      // DataTy is the overloaded type
      Type *DataTy = cast<PointerType>(Ptr->getType())->getElementType();
      Assert(DataTy == Val->getType(),
             "masked_store: storee must match pointer type", Call);
      Assert(Mask->getType()->getVectorNumElements() ==
                 DataTy->getVectorNumElements(),
             "masked_store: vector mask must be same length as data", Call);
      break;
    }
  
    case Intrinsic::experimental_guard: {
      Assert(isa<CallInst>(Call), "experimental_guard cannot be invoked", Call);
      Assert(Call.countOperandBundlesOfType(LLVMContext::OB_deopt) == 1,
             "experimental_guard must have exactly one "
             "\"deopt\" operand bundle");
      break;
    }
  
    case Intrinsic::experimental_deoptimize: {
      Assert(isa<CallInst>(Call), "experimental_deoptimize cannot be invoked",
             Call);
      Assert(Call.countOperandBundlesOfType(LLVMContext::OB_deopt) == 1,
             "experimental_deoptimize must have exactly one "
             "\"deopt\" operand bundle");
      Assert(Call.getType() == Call.getFunction()->getReturnType(),
             "experimental_deoptimize return type must match caller return type");
  
      if (isa<CallInst>(Call)) {
        auto *RI = dyn_cast<ReturnInst>(Call.getNextNode());
        Assert(RI,
               "calls to experimental_deoptimize must be followed by a return");
  
        if (!Call.getType()->isVoidTy() && RI)
          Assert(RI->getReturnValue() == &Call,
                 "calls to experimental_deoptimize must be followed by a return "
                 "of the value computed by experimental_deoptimize");
      }
  
      break;
    }
    case Intrinsic::sadd_sat:
    case Intrinsic::uadd_sat:
    case Intrinsic::ssub_sat:
    case Intrinsic::usub_sat: {
      Value *Op1 = Call.getArgOperand(0);
      Value *Op2 = Call.getArgOperand(1);
      Assert(Op1->getType()->isIntOrIntVectorTy(),
             "first operand of [us][add|sub]_sat must be an int type or vector "
             "of ints");
      Assert(Op2->getType()->isIntOrIntVectorTy(),
             "second operand of [us][add|sub]_sat must be an int type or vector "
             "of ints");
      break;
    }
    case Intrinsic::smul_fix:
    case Intrinsic::smul_fix_sat:
    case Intrinsic::umul_fix: {
      Value *Op1 = Call.getArgOperand(0);
      Value *Op2 = Call.getArgOperand(1);
      Assert(Op1->getType()->isIntOrIntVectorTy(),
             "first operand of [us]mul_fix[_sat] must be an int type or vector "
             "of ints");
      Assert(Op2->getType()->isIntOrIntVectorTy(),
             "second operand of [us]mul_fix_[sat] must be an int type or vector "
             "of ints");
  
      auto *Op3 = cast<ConstantInt>(Call.getArgOperand(2));
      Assert(Op3->getType()->getBitWidth() <= 32,
             "third argument of [us]mul_fix[_sat] must fit within 32 bits");
  
      if (ID == Intrinsic::smul_fix || ID == Intrinsic::smul_fix_sat) {
        Assert(
            Op3->getZExtValue() < Op1->getType()->getScalarSizeInBits(),
            "the scale of smul_fix[_sat] must be less than the width of the operands");
      } else {
        Assert(Op3->getZExtValue() <= Op1->getType()->getScalarSizeInBits(),
               "the scale of umul_fix[_sat] must be less than or equal to the width of "
               "the operands");
      }
      break;
    }
    case Intrinsic::lround:
    case Intrinsic::llround:
    case Intrinsic::lrint:
    case Intrinsic::llrint: {
      Type *ValTy = Call.getArgOperand(0)->getType();
      Type *ResultTy = Call.getType();
      Assert(!ValTy->isVectorTy() && !ResultTy->isVectorTy(),
             "Intrinsic does not support vectors", &Call);
      break;
    }
    };
  }
  
  /// Carefully grab the subprogram from a local scope.
  ///
  /// This carefully grabs the subprogram from a local scope, avoiding the
  /// built-in assertions that would typically fire.
  static DISubprogram *getSubprogram(Metadata *LocalScope) {
    if (!LocalScope)
      return nullptr;
  
    if (auto *SP = dyn_cast<DISubprogram>(LocalScope))
      return SP;
  
    if (auto *LB = dyn_cast<DILexicalBlockBase>(LocalScope))
      return getSubprogram(LB->getRawScope());
  
    // Just return null; broken scope chains are checked elsewhere.
    assert(!isa<DILocalScope>(LocalScope) && "Unknown type of local scope");
    return nullptr;
  }
  
  void Verifier::visitConstrainedFPIntrinsic(ConstrainedFPIntrinsic &FPI) {
    unsigned NumOperands = FPI.getNumArgOperands();
    bool HasExceptionMD = false;
    bool HasRoundingMD = false;
    switch (FPI.getIntrinsicID()) {
    case Intrinsic::experimental_constrained_sqrt:
    case Intrinsic::experimental_constrained_sin:
    case Intrinsic::experimental_constrained_cos:
    case Intrinsic::experimental_constrained_exp:
    case Intrinsic::experimental_constrained_exp2:
    case Intrinsic::experimental_constrained_log:
    case Intrinsic::experimental_constrained_log10:
    case Intrinsic::experimental_constrained_log2:
    case Intrinsic::experimental_constrained_rint:
    case Intrinsic::experimental_constrained_nearbyint:
    case Intrinsic::experimental_constrained_ceil:
    case Intrinsic::experimental_constrained_floor:
    case Intrinsic::experimental_constrained_round:
    case Intrinsic::experimental_constrained_trunc:
      Assert((NumOperands == 3), "invalid arguments for constrained FP intrinsic",
             &FPI);
      HasExceptionMD = true;
      HasRoundingMD = true;
      break;
  
    case Intrinsic::experimental_constrained_fma:
      Assert((NumOperands == 5), "invalid arguments for constrained FP intrinsic",
             &FPI);
      HasExceptionMD = true;
      HasRoundingMD = true;
      break;
  
    case Intrinsic::experimental_constrained_fadd:
    case Intrinsic::experimental_constrained_fsub:
    case Intrinsic::experimental_constrained_fmul:
    case Intrinsic::experimental_constrained_fdiv:
    case Intrinsic::experimental_constrained_frem:
    case Intrinsic::experimental_constrained_pow:
    case Intrinsic::experimental_constrained_powi:
    case Intrinsic::experimental_constrained_maxnum:
    case Intrinsic::experimental_constrained_minnum:
      Assert((NumOperands == 4), "invalid arguments for constrained FP intrinsic",
             &FPI);
      HasExceptionMD = true;
      HasRoundingMD = true;
      break;
  
    case Intrinsic::experimental_constrained_fptrunc:
    case Intrinsic::experimental_constrained_fpext: {
      if (FPI.getIntrinsicID() == Intrinsic::experimental_constrained_fptrunc) {
        Assert((NumOperands == 3),
               "invalid arguments for constrained FP intrinsic", &FPI);
        HasRoundingMD = true;
      } else {
        Assert((NumOperands == 2),
               "invalid arguments for constrained FP intrinsic", &FPI);
      }
      HasExceptionMD = true;
  
      Value *Operand = FPI.getArgOperand(0);
      Type *OperandTy = Operand->getType();
      Value *Result = &FPI;
      Type *ResultTy = Result->getType();
      Assert(OperandTy->isFPOrFPVectorTy(),
             "Intrinsic first argument must be FP or FP vector", &FPI);
      Assert(ResultTy->isFPOrFPVectorTy(),
             "Intrinsic result must be FP or FP vector", &FPI);
      Assert(OperandTy->isVectorTy() == ResultTy->isVectorTy(),
             "Intrinsic first argument and result disagree on vector use", &FPI);
      if (OperandTy->isVectorTy()) {
        auto *OperandVecTy = cast<VectorType>(OperandTy);
        auto *ResultVecTy = cast<VectorType>(ResultTy);
        Assert(OperandVecTy->getNumElements() == ResultVecTy->getNumElements(),
               "Intrinsic first argument and result vector lengths must be equal",
               &FPI);
      }
      if (FPI.getIntrinsicID() == Intrinsic::experimental_constrained_fptrunc) {
        Assert(OperandTy->getScalarSizeInBits() > ResultTy->getScalarSizeInBits(),
               "Intrinsic first argument's type must be larger than result type",
               &FPI);
      } else {
        Assert(OperandTy->getScalarSizeInBits() < ResultTy->getScalarSizeInBits(),
               "Intrinsic first argument's type must be smaller than result type",
               &FPI);
      }
    } 
      break;
  
    default:
      llvm_unreachable("Invalid constrained FP intrinsic!");
    }
  
    // If a non-metadata argument is passed in a metadata slot then the
    // error will be caught earlier when the incorrect argument doesn't
    // match the specification in the intrinsic call table. Thus, no
    // argument type check is needed here.
  
    if (HasExceptionMD) {
      Assert(FPI.getExceptionBehavior().hasValue(),
             "invalid exception behavior argument", &FPI);
    }
    if (HasRoundingMD) {
      Assert(FPI.getRoundingMode().hasValue(),
             "invalid rounding mode argument", &FPI);
    }
  }
  
  void Verifier::visitDbgIntrinsic(StringRef Kind, DbgVariableIntrinsic &DII) {
    auto *MD = cast<MetadataAsValue>(DII.getArgOperand(0))->getMetadata();
    AssertDI(isa<ValueAsMetadata>(MD) ||
               (isa<MDNode>(MD) && !cast<MDNode>(MD)->getNumOperands()),
           "invalid llvm.dbg." + Kind + " intrinsic address/value", &DII, MD);
    AssertDI(isa<DILocalVariable>(DII.getRawVariable()),
           "invalid llvm.dbg." + Kind + " intrinsic variable", &DII,
           DII.getRawVariable());
    AssertDI(isa<DIExpression>(DII.getRawExpression()),
           "invalid llvm.dbg." + Kind + " intrinsic expression", &DII,
           DII.getRawExpression());
  
    // Ignore broken !dbg attachments; they're checked elsewhere.
    if (MDNode *N = DII.getDebugLoc().getAsMDNode())
      if (!isa<DILocation>(N))
        return;
  
    BasicBlock *BB = DII.getParent();
    Function *F = BB ? BB->getParent() : nullptr;
  
    // The scopes for variables and !dbg attachments must agree.
    DILocalVariable *Var = DII.getVariable();
    DILocation *Loc = DII.getDebugLoc();
    AssertDI(Loc, "llvm.dbg." + Kind + " intrinsic requires a !dbg attachment",
             &DII, BB, F);
  
    DISubprogram *VarSP = getSubprogram(Var->getRawScope());
    DISubprogram *LocSP = getSubprogram(Loc->getRawScope());
    if (!VarSP || !LocSP)
      return; // Broken scope chains are checked elsewhere.
  
    AssertDI(VarSP == LocSP, "mismatched subprogram between llvm.dbg." + Kind +
                                 " variable and !dbg attachment",
             &DII, BB, F, Var, Var->getScope()->getSubprogram(), Loc,
             Loc->getScope()->getSubprogram());
  
    // This check is redundant with one in visitLocalVariable().
    AssertDI(isType(Var->getRawType()), "invalid type ref", Var,
             Var->getRawType());
    if (auto *Type = dyn_cast_or_null<DIType>(Var->getRawType()))
      if (Type->isBlockByrefStruct())
        AssertDI(DII.getExpression() && DII.getExpression()->getNumElements(),
                 "BlockByRef variable without complex expression", Var, &DII);
  
    verifyFnArgs(DII);
  }
  
  void Verifier::visitDbgLabelIntrinsic(StringRef Kind, DbgLabelInst &DLI) {
    AssertDI(isa<DILabel>(DLI.getRawLabel()),
           "invalid llvm.dbg." + Kind + " intrinsic variable", &DLI,
           DLI.getRawLabel());
  
    // Ignore broken !dbg attachments; they're checked elsewhere.
    if (MDNode *N = DLI.getDebugLoc().getAsMDNode())
      if (!isa<DILocation>(N))
        return;
  
    BasicBlock *BB = DLI.getParent();
    Function *F = BB ? BB->getParent() : nullptr;
  
    // The scopes for variables and !dbg attachments must agree.
    DILabel *Label = DLI.getLabel();
    DILocation *Loc = DLI.getDebugLoc();
    Assert(Loc, "llvm.dbg." + Kind + " intrinsic requires a !dbg attachment",
           &DLI, BB, F);
  
    DISubprogram *LabelSP = getSubprogram(Label->getRawScope());
    DISubprogram *LocSP = getSubprogram(Loc->getRawScope());
    if (!LabelSP || !LocSP)
      return;
  
    AssertDI(LabelSP == LocSP, "mismatched subprogram between llvm.dbg." + Kind +
                               " label and !dbg attachment",
             &DLI, BB, F, Label, Label->getScope()->getSubprogram(), Loc,
             Loc->getScope()->getSubprogram());
  }
  
  void Verifier::verifyFragmentExpression(const DbgVariableIntrinsic &I) {
    DILocalVariable *V = dyn_cast_or_null<DILocalVariable>(I.getRawVariable());
    DIExpression *E = dyn_cast_or_null<DIExpression>(I.getRawExpression());
  
    // We don't know whether this intrinsic verified correctly.
    if (!V || !E || !E->isValid())
      return;
  
    // Nothing to do if this isn't a DW_OP_LLVM_fragment expression.
    auto Fragment = E->getFragmentInfo();
    if (!Fragment)
      return;
  
    // The frontend helps out GDB by emitting the members of local anonymous
    // unions as artificial local variables with shared storage. When SROA splits
    // the storage for artificial local variables that are smaller than the entire
    // union, the overhang piece will be outside of the allotted space for the
    // variable and this check fails.
    // FIXME: Remove this check as soon as clang stops doing this; it hides bugs.
    if (V->isArtificial())
      return;
  
    verifyFragmentExpression(*V, *Fragment, &I);
  }
  
  template <typename ValueOrMetadata>
  void Verifier::verifyFragmentExpression(const DIVariable &V,
                                          DIExpression::FragmentInfo Fragment,
                                          ValueOrMetadata *Desc) {
    // If there's no size, the type is broken, but that should be checked
    // elsewhere.
    auto VarSize = V.getSizeInBits();
    if (!VarSize)
      return;
  
    unsigned FragSize = Fragment.SizeInBits;
    unsigned FragOffset = Fragment.OffsetInBits;
    AssertDI(FragSize + FragOffset <= *VarSize,
           "fragment is larger than or outside of variable", Desc, &V);
    AssertDI(FragSize != *VarSize, "fragment covers entire variable", Desc, &V);
  }
  
  void Verifier::verifyFnArgs(const DbgVariableIntrinsic &I) {
    // This function does not take the scope of noninlined function arguments into
    // account. Don't run it if current function is nodebug, because it may
    // contain inlined debug intrinsics.
    if (!HasDebugInfo)
      return;
  
    // For performance reasons only check non-inlined ones.
    if (I.getDebugLoc()->getInlinedAt())
      return;
  
    DILocalVariable *Var = I.getVariable();
    AssertDI(Var, "dbg intrinsic without variable");
  
    unsigned ArgNo = Var->getArg();
    if (!ArgNo)
      return;
  
    // Verify there are no duplicate function argument debug info entries.
    // These will cause hard-to-debug assertions in the DWARF backend.
    if (DebugFnArgs.size() < ArgNo)
      DebugFnArgs.resize(ArgNo, nullptr);
  
    auto *Prev = DebugFnArgs[ArgNo - 1];
    DebugFnArgs[ArgNo - 1] = Var;
    AssertDI(!Prev || (Prev == Var), "conflicting debug info for argument", &I,
             Prev, Var);
  }
  
  void Verifier::verifyCompileUnits() {
    // When more than one Module is imported into the same context, such as during
    // an LTO build before linking the modules, ODR type uniquing may cause types
    // to point to a different CU. This check does not make sense in this case.
    if (M.getContext().isODRUniquingDebugTypes())
      return;
    auto *CUs = M.getNamedMetadata("llvm.dbg.cu");
    SmallPtrSet<const Metadata *, 2> Listed;
    if (CUs)
      Listed.insert(CUs->op_begin(), CUs->op_end());
    for (auto *CU : CUVisited)
      AssertDI(Listed.count(CU), "DICompileUnit not listed in llvm.dbg.cu", CU);
    CUVisited.clear();
  }
  
  void Verifier::verifyDeoptimizeCallingConvs() {
    if (DeoptimizeDeclarations.empty())
      return;
  
    const Function *First = DeoptimizeDeclarations[0];
    for (auto *F : makeArrayRef(DeoptimizeDeclarations).slice(1)) {
      Assert(First->getCallingConv() == F->getCallingConv(),
             "All llvm.experimental.deoptimize declarations must have the same "
             "calling convention",
             First, F);
    }
  }
  
  void Verifier::verifySourceDebugInfo(const DICompileUnit &U, const DIFile &F) {
    bool HasSource = F.getSource().hasValue();
    if (!HasSourceDebugInfo.count(&U))
      HasSourceDebugInfo[&U] = HasSource;
    AssertDI(HasSource == HasSourceDebugInfo[&U],
             "inconsistent use of embedded source");
  }
  
  //===----------------------------------------------------------------------===//
  //  Implement the public interfaces to this file...
  //===----------------------------------------------------------------------===//
  
  bool llvm::verifyFunction(const Function &f, raw_ostream *OS) {
    Function &F = const_cast<Function &>(f);
  
    // Don't use a raw_null_ostream.  Printing IR is expensive.
    Verifier V(OS, /*ShouldTreatBrokenDebugInfoAsError=*/true, *f.getParent());
  
    // Note that this function's return value is inverted from what you would
    // expect of a function called "verify".
    return !V.verify(F);
  }
  
  bool llvm::verifyModule(const Module &M, raw_ostream *OS,
                          bool *BrokenDebugInfo) {
    // Don't use a raw_null_ostream.  Printing IR is expensive.
    Verifier V(OS, /*ShouldTreatBrokenDebugInfoAsError=*/!BrokenDebugInfo, M);
  
    bool Broken = false;
    for (const Function &F : M)
      Broken |= !V.verify(F);
  
    Broken |= !V.verify();
    if (BrokenDebugInfo)
      *BrokenDebugInfo = V.hasBrokenDebugInfo();
    // Note that this function's return value is inverted from what you would
    // expect of a function called "verify".
    return Broken;
  }
  
  namespace {
  
  struct VerifierLegacyPass : public FunctionPass {
    static char ID;
  
    std::unique_ptr<Verifier> V;
    bool FatalErrors = true;
  
    VerifierLegacyPass() : FunctionPass(ID) {
      initializeVerifierLegacyPassPass(*PassRegistry::getPassRegistry());
    }
    explicit VerifierLegacyPass(bool FatalErrors)
        : FunctionPass(ID),
          FatalErrors(FatalErrors) {
      initializeVerifierLegacyPassPass(*PassRegistry::getPassRegistry());
    }
  
    bool doInitialization(Module &M) override {
      V = llvm::make_unique<Verifier>(
          &dbgs(), /*ShouldTreatBrokenDebugInfoAsError=*/false, M);
      return false;
    }
  
    bool runOnFunction(Function &F) override {
      if (!V->verify(F) && FatalErrors) {
        errs() << "in function " << F.getName() << '\n'; 
        report_fatal_error("Broken function found, compilation aborted!");
      }
      return false;
    }
  
    bool doFinalization(Module &M) override {
      bool HasErrors = false;
      for (Function &F : M)
        if (F.isDeclaration())
          HasErrors |= !V->verify(F);
  
      HasErrors |= !V->verify();
      if (FatalErrors && (HasErrors || V->hasBrokenDebugInfo()))
        report_fatal_error("Broken module found, compilation aborted!");
      return false;
    }
  
    void getAnalysisUsage(AnalysisUsage &AU) const override {
      AU.setPreservesAll();
    }
  };
  
  } // end anonymous namespace
  
  /// Helper to issue failure from the TBAA verification
  template <typename... Tys> void TBAAVerifier::CheckFailed(Tys &&... Args) {
    if (Diagnostic)
      return Diagnostic->CheckFailed(Args...);
  }
  
  #define AssertTBAA(C, ...)                                                     \
    do {                                                                         \
      if (!(C)) {                                                                \
        CheckFailed(__VA_ARGS__);                                                \
        return false;                                                            \
      }                                                                          \
    } while (false)
  
  /// Verify that \p BaseNode can be used as the "base type" in the struct-path
  /// TBAA scheme.  This means \p BaseNode is either a scalar node, or a
  /// struct-type node describing an aggregate data structure (like a struct).
  TBAAVerifier::TBAABaseNodeSummary
  TBAAVerifier::verifyTBAABaseNode(Instruction &I, const MDNode *BaseNode,
                                   bool IsNewFormat) {
    if (BaseNode->getNumOperands() < 2) {
      CheckFailed("Base nodes must have at least two operands", &I, BaseNode);
      return {true, ~0u};
    }
  
    auto Itr = TBAABaseNodes.find(BaseNode);
    if (Itr != TBAABaseNodes.end())
      return Itr->second;
  
    auto Result = verifyTBAABaseNodeImpl(I, BaseNode, IsNewFormat);
    auto InsertResult = TBAABaseNodes.insert({BaseNode, Result});
    (void)InsertResult;
    assert(InsertResult.second && "We just checked!");
    return Result;
  }
  
  TBAAVerifier::TBAABaseNodeSummary
  TBAAVerifier::verifyTBAABaseNodeImpl(Instruction &I, const MDNode *BaseNode,
                                       bool IsNewFormat) {
    const TBAAVerifier::TBAABaseNodeSummary InvalidNode = {true, ~0u};
  
    if (BaseNode->getNumOperands() == 2) {
      // Scalar nodes can only be accessed at offset 0.
      return isValidScalarTBAANode(BaseNode)
                 ? TBAAVerifier::TBAABaseNodeSummary({false, 0})
                 : InvalidNode;
    }
  
    if (IsNewFormat) {
      if (BaseNode->getNumOperands() % 3 != 0) {
        CheckFailed("Access tag nodes must have the number of operands that is a "
                    "multiple of 3!", BaseNode);
        return InvalidNode;
      }
    } else {
      if (BaseNode->getNumOperands() % 2 != 1) {
        CheckFailed("Struct tag nodes must have an odd number of operands!",
                    BaseNode);
        return InvalidNode;
      }
    }
  
    // Check the type size field.
    if (IsNewFormat) {
      auto *TypeSizeNode = mdconst::dyn_extract_or_null<ConstantInt>(
          BaseNode->getOperand(1));
      if (!TypeSizeNode) {
        CheckFailed("Type size nodes must be constants!", &I, BaseNode);
        return InvalidNode;
      }
    }
  
    // Check the type name field. In the new format it can be anything.
    if (!IsNewFormat && !isa<MDString>(BaseNode->getOperand(0))) {
      CheckFailed("Struct tag nodes have a string as their first operand",
                  BaseNode);
      return InvalidNode;
    }
  
    bool Failed = false;
  
    Optional<APInt> PrevOffset;
    unsigned BitWidth = ~0u;
  
    // We've already checked that BaseNode is not a degenerate root node with one
    // operand in \c verifyTBAABaseNode, so this loop should run at least once.
    unsigned FirstFieldOpNo = IsNewFormat ? 3 : 1;
    unsigned NumOpsPerField = IsNewFormat ? 3 : 2;
    for (unsigned Idx = FirstFieldOpNo; Idx < BaseNode->getNumOperands();
             Idx += NumOpsPerField) {
      const MDOperand &FieldTy = BaseNode->getOperand(Idx);
      const MDOperand &FieldOffset = BaseNode->getOperand(Idx + 1);
      if (!isa<MDNode>(FieldTy)) {
        CheckFailed("Incorrect field entry in struct type node!", &I, BaseNode);
        Failed = true;
        continue;
      }
  
      auto *OffsetEntryCI =
          mdconst::dyn_extract_or_null<ConstantInt>(FieldOffset);
      if (!OffsetEntryCI) {
        CheckFailed("Offset entries must be constants!", &I, BaseNode);
        Failed = true;
        continue;
      }
  
      if (BitWidth == ~0u)
        BitWidth = OffsetEntryCI->getBitWidth();
  
      if (OffsetEntryCI->getBitWidth() != BitWidth) {
        CheckFailed(
            "Bitwidth between the offsets and struct type entries must match", &I,
            BaseNode);
        Failed = true;
        continue;
      }
  
      // NB! As far as I can tell, we generate a non-strictly increasing offset
      // sequence only from structs that have zero size bit fields.  When
      // recursing into a contained struct in \c getFieldNodeFromTBAABaseNode we
      // pick the field lexically the latest in struct type metadata node.  This
      // mirrors the actual behavior of the alias analysis implementation.
      bool IsAscending =
          !PrevOffset || PrevOffset->ule(OffsetEntryCI->getValue());
  
      if (!IsAscending) {
        CheckFailed("Offsets must be increasing!", &I, BaseNode);
        Failed = true;
      }
  
      PrevOffset = OffsetEntryCI->getValue();
  
      if (IsNewFormat) {
        auto *MemberSizeNode = mdconst::dyn_extract_or_null<ConstantInt>(
            BaseNode->getOperand(Idx + 2));
        if (!MemberSizeNode) {
          CheckFailed("Member size entries must be constants!", &I, BaseNode);
          Failed = true;
          continue;
        }
      }
    }
  
    return Failed ? InvalidNode
                  : TBAAVerifier::TBAABaseNodeSummary(false, BitWidth);
  }
  
  static bool IsRootTBAANode(const MDNode *MD) {
    return MD->getNumOperands() < 2;
  }
  
  static bool IsScalarTBAANodeImpl(const MDNode *MD,
                                   SmallPtrSetImpl<const MDNode *> &Visited) {
    if (MD->getNumOperands() != 2 && MD->getNumOperands() != 3)
      return false;
  
    if (!isa<MDString>(MD->getOperand(0)))
      return false;
  
    if (MD->getNumOperands() == 3) {
      auto *Offset = mdconst::dyn_extract<ConstantInt>(MD->getOperand(2));
      if (!(Offset && Offset->isZero() && isa<MDString>(MD->getOperand(0))))
        return false;
    }
  
    auto *Parent = dyn_cast_or_null<MDNode>(MD->getOperand(1));
    return Parent && Visited.insert(Parent).second &&
           (IsRootTBAANode(Parent) || IsScalarTBAANodeImpl(Parent, Visited));
  }
  
  bool TBAAVerifier::isValidScalarTBAANode(const MDNode *MD) {
    auto ResultIt = TBAAScalarNodes.find(MD);
    if (ResultIt != TBAAScalarNodes.end())
      return ResultIt->second;
  
    SmallPtrSet<const MDNode *, 4> Visited;
    bool Result = IsScalarTBAANodeImpl(MD, Visited);
    auto InsertResult = TBAAScalarNodes.insert({MD, Result});
    (void)InsertResult;
    assert(InsertResult.second && "Just checked!");
  
    return Result;
  }
  
  /// Returns the field node at the offset \p Offset in \p BaseNode.  Update \p
  /// Offset in place to be the offset within the field node returned.
  ///
  /// We assume we've okayed \p BaseNode via \c verifyTBAABaseNode.
  MDNode *TBAAVerifier::getFieldNodeFromTBAABaseNode(Instruction &I,
                                                     const MDNode *BaseNode,
                                                     APInt &Offset,
                                                     bool IsNewFormat) {
    assert(BaseNode->getNumOperands() >= 2 && "Invalid base node!");
  
    // Scalar nodes have only one possible "field" -- their parent in the access
    // hierarchy.  Offset must be zero at this point, but our caller is supposed
    // to Assert that.
    if (BaseNode->getNumOperands() == 2)
      return cast<MDNode>(BaseNode->getOperand(1));
  
    unsigned FirstFieldOpNo = IsNewFormat ? 3 : 1;
    unsigned NumOpsPerField = IsNewFormat ? 3 : 2;
    for (unsigned Idx = FirstFieldOpNo; Idx < BaseNode->getNumOperands();
             Idx += NumOpsPerField) {
      auto *OffsetEntryCI =
          mdconst::extract<ConstantInt>(BaseNode->getOperand(Idx + 1));
      if (OffsetEntryCI->getValue().ugt(Offset)) {
        if (Idx == FirstFieldOpNo) {
          CheckFailed("Could not find TBAA parent in struct type node", &I,
                      BaseNode, &Offset);
          return nullptr;
        }
  
        unsigned PrevIdx = Idx - NumOpsPerField;
        auto *PrevOffsetEntryCI =
            mdconst::extract<ConstantInt>(BaseNode->getOperand(PrevIdx + 1));
        Offset -= PrevOffsetEntryCI->getValue();
        return cast<MDNode>(BaseNode->getOperand(PrevIdx));
      }
    }
  
    unsigned LastIdx = BaseNode->getNumOperands() - NumOpsPerField;
    auto *LastOffsetEntryCI = mdconst::extract<ConstantInt>(
        BaseNode->getOperand(LastIdx + 1));
    Offset -= LastOffsetEntryCI->getValue();
    return cast<MDNode>(BaseNode->getOperand(LastIdx));
  }
  
  static bool isNewFormatTBAATypeNode(llvm::MDNode *Type) {
    if (!Type || Type->getNumOperands() < 3)
      return false;
  
    // In the new format type nodes shall have a reference to the parent type as
    // its first operand.
    MDNode *Parent = dyn_cast_or_null<MDNode>(Type->getOperand(0));
    if (!Parent)
      return false;
  
    return true;
  }
  
  bool TBAAVerifier::visitTBAAMetadata(Instruction &I, const MDNode *MD) {
    AssertTBAA(isa<LoadInst>(I) || isa<StoreInst>(I) || isa<CallInst>(I) ||
                   isa<VAArgInst>(I) || isa<AtomicRMWInst>(I) ||
                   isa<AtomicCmpXchgInst>(I),
               "This instruction shall not have a TBAA access tag!", &I);
  
    bool IsStructPathTBAA =
        isa<MDNode>(MD->getOperand(0)) && MD->getNumOperands() >= 3;
  
    AssertTBAA(
        IsStructPathTBAA,
        "Old-style TBAA is no longer allowed, use struct-path TBAA instead", &I);
  
    MDNode *BaseNode = dyn_cast_or_null<MDNode>(MD->getOperand(0));
    MDNode *AccessType = dyn_cast_or_null<MDNode>(MD->getOperand(1));
  
    bool IsNewFormat = isNewFormatTBAATypeNode(AccessType);
  
    if (IsNewFormat) {
      AssertTBAA(MD->getNumOperands() == 4 || MD->getNumOperands() == 5,
                 "Access tag metadata must have either 4 or 5 operands", &I, MD);
    } else {
      AssertTBAA(MD->getNumOperands() < 5,
                 "Struct tag metadata must have either 3 or 4 operands", &I, MD);
    }
  
    // Check the access size field.
    if (IsNewFormat) {
      auto *AccessSizeNode = mdconst::dyn_extract_or_null<ConstantInt>(
          MD->getOperand(3));
      AssertTBAA(AccessSizeNode, "Access size field must be a constant", &I, MD);
    }
  
    // Check the immutability flag.
    unsigned ImmutabilityFlagOpNo = IsNewFormat ? 4 : 3;
    if (MD->getNumOperands() == ImmutabilityFlagOpNo + 1) {
      auto *IsImmutableCI = mdconst::dyn_extract_or_null<ConstantInt>(
          MD->getOperand(ImmutabilityFlagOpNo));
      AssertTBAA(IsImmutableCI,
                 "Immutability tag on struct tag metadata must be a constant",
                 &I, MD);
      AssertTBAA(
          IsImmutableCI->isZero() || IsImmutableCI->isOne(),
          "Immutability part of the struct tag metadata must be either 0 or 1",
          &I, MD);
    }
  
    AssertTBAA(BaseNode && AccessType,
               "Malformed struct tag metadata: base and access-type "
               "should be non-null and point to Metadata nodes",
               &I, MD, BaseNode, AccessType);
  
    if (!IsNewFormat) {
      AssertTBAA(isValidScalarTBAANode(AccessType),
                 "Access type node must be a valid scalar type", &I, MD,
                 AccessType);
    }
  
    auto *OffsetCI = mdconst::dyn_extract_or_null<ConstantInt>(MD->getOperand(2));
    AssertTBAA(OffsetCI, "Offset must be constant integer", &I, MD);
  
    APInt Offset = OffsetCI->getValue();
    bool SeenAccessTypeInPath = false;
  
    SmallPtrSet<MDNode *, 4> StructPath;
  
    for (/* empty */; BaseNode && !IsRootTBAANode(BaseNode);
         BaseNode = getFieldNodeFromTBAABaseNode(I, BaseNode, Offset,
                                                 IsNewFormat)) {
      if (!StructPath.insert(BaseNode).second) {
        CheckFailed("Cycle detected in struct path", &I, MD);
        return false;
      }
  
      bool Invalid;
      unsigned BaseNodeBitWidth;
      std::tie(Invalid, BaseNodeBitWidth) = verifyTBAABaseNode(I, BaseNode,
                                                               IsNewFormat);
  
      // If the base node is invalid in itself, then we've already printed all the
      // errors we wanted to print.
      if (Invalid)
        return false;
  
      SeenAccessTypeInPath |= BaseNode == AccessType;
  
      if (isValidScalarTBAANode(BaseNode) || BaseNode == AccessType)
        AssertTBAA(Offset == 0, "Offset not zero at the point of scalar access",
                   &I, MD, &Offset);
  
      AssertTBAA(BaseNodeBitWidth == Offset.getBitWidth() ||
                     (BaseNodeBitWidth == 0 && Offset == 0) ||
                     (IsNewFormat && BaseNodeBitWidth == ~0u),
                 "Access bit-width not the same as description bit-width", &I, MD,
                 BaseNodeBitWidth, Offset.getBitWidth());
  
      if (IsNewFormat && SeenAccessTypeInPath)
        break;
    }
  
    AssertTBAA(SeenAccessTypeInPath, "Did not see access type in access path!",
               &I, MD);
    return true;
  }
  
  char VerifierLegacyPass::ID = 0;
  INITIALIZE_PASS(VerifierLegacyPass, "verify", "Module Verifier", false, false)
  
  FunctionPass *llvm::createVerifierPass(bool FatalErrors) {
    return new VerifierLegacyPass(FatalErrors);
  }
  
  AnalysisKey VerifierAnalysis::Key;
  VerifierAnalysis::Result VerifierAnalysis::run(Module &M,
                                                 ModuleAnalysisManager &) {
    Result Res;
    Res.IRBroken = llvm::verifyModule(M, &dbgs(), &Res.DebugInfoBroken);
    return Res;
  }
  
  VerifierAnalysis::Result VerifierAnalysis::run(Function &F,
                                                 FunctionAnalysisManager &) {
    return { llvm::verifyFunction(F, &dbgs()), false };
  }
  
  PreservedAnalyses VerifierPass::run(Module &M, ModuleAnalysisManager &AM) {
    auto Res = AM.getResult<VerifierAnalysis>(M);
    if (FatalErrors && (Res.IRBroken || Res.DebugInfoBroken))
      report_fatal_error("Broken module found, compilation aborted!");
  
    return PreservedAnalyses::all();
  }
  
  PreservedAnalyses VerifierPass::run(Function &F, FunctionAnalysisManager &AM) {
    auto res = AM.getResult<VerifierAnalysis>(F);
    if (res.IRBroken && FatalErrors)
      report_fatal_error("Broken function found, compilation aborted!");
  
    return PreservedAnalyses::all();
  }
  