text: //===-- LLParser.cpp - Parser Class ---------------------------------------===//
  //
  //                     The LLVM Compiler Infrastructure
  //
  // This file is distributed under the University of Illinois Open Source
  // License. See LICENSE.TXT for details.
  //
  //===----------------------------------------------------------------------===//
  //
  //  This file defines the parser class for .ll files.
  //
  //===----------------------------------------------------------------------===//
  
  #include "LLParser.h"
  #include "llvm/ADT/SmallPtrSet.h"
  #include "llvm/IR/AutoUpgrade.h"
  #include "llvm/IR/CallingConv.h"
  #include "llvm/IR/Constants.h"
  #include "llvm/IR/DerivedTypes.h"
  #include "llvm/IR/InlineAsm.h"
  #include "llvm/IR/Instructions.h"
  #include "llvm/IR/LLVMContext.h"
  #include "llvm/IR/Module.h"
  #include "llvm/IR/Operator.h"
  #include "llvm/IR/ValueSymbolTable.h"
  #include "llvm/Support/ErrorHandling.h"
  #include "llvm/Support/SaveAndRestore.h"
  #include "llvm/Support/raw_ostream.h"
  using namespace llvm;
  
  static std::string getTypeString(Type *T) {
    std::string Result;
    raw_string_ostream Tmp(Result);
    Tmp << *T;
    return Tmp.str();
  }
  
  /// Run: module ::= toplevelentity*
  bool LLParser::Run() {
    // Prime the lexer.
    Lex.Lex();
  
    return ParseTopLevelEntities() ||
           ValidateEndOfModule();
  }
  
  /// ValidateEndOfModule - Do final validity and sanity checks at the end of the
  /// module.
  bool LLParser::ValidateEndOfModule() {
    for (unsigned I = 0, E = InstsWithTBAATag.size(); I < E; I++)
      UpgradeInstWithTBAATag(InstsWithTBAATag[I]);
  
    // Handle any function attribute group forward references.
    for (std::map<Value*, std::vector<unsigned> >::iterator
           I = ForwardRefAttrGroups.begin(), E = ForwardRefAttrGroups.end();
           I != E; ++I) {
      Value *V = I->first;
      std::vector<unsigned> &Vec = I->second;
      AttrBuilder B;
  
      for (std::vector<unsigned>::iterator VI = Vec.begin(), VE = Vec.end();
           VI != VE; ++VI)
        B.merge(NumberedAttrBuilders[*VI]);
  
      if (Function *Fn = dyn_cast<Function>(V)) {
        AttributeSet AS = Fn->getAttributes();
        AttrBuilder FnAttrs(AS.getFnAttributes(), AttributeSet::FunctionIndex);
        AS = AS.removeAttributes(Context, AttributeSet::FunctionIndex,
                                 AS.getFnAttributes());
  
        FnAttrs.merge(B);
  
        // If the alignment was parsed as an attribute, move to the alignment
        // field.
        if (FnAttrs.hasAlignmentAttr()) {
          Fn->setAlignment(FnAttrs.getAlignment());
          FnAttrs.removeAttribute(Attribute::Alignment);
        }
  
        AS = AS.addAttributes(Context, AttributeSet::FunctionIndex,
                              AttributeSet::get(Context,
                                                AttributeSet::FunctionIndex,
                                                FnAttrs));
        Fn->setAttributes(AS);
      } else if (CallInst *CI = dyn_cast<CallInst>(V)) {
        AttributeSet AS = CI->getAttributes();
        AttrBuilder FnAttrs(AS.getFnAttributes(), AttributeSet::FunctionIndex);
        AS = AS.removeAttributes(Context, AttributeSet::FunctionIndex,
                                 AS.getFnAttributes());
        FnAttrs.merge(B);
        AS = AS.addAttributes(Context, AttributeSet::FunctionIndex,
                              AttributeSet::get(Context,
                                                AttributeSet::FunctionIndex,
                                                FnAttrs));
        CI->setAttributes(AS);
      } else if (InvokeInst *II = dyn_cast<InvokeInst>(V)) {
        AttributeSet AS = II->getAttributes();
        AttrBuilder FnAttrs(AS.getFnAttributes(), AttributeSet::FunctionIndex);
        AS = AS.removeAttributes(Context, AttributeSet::FunctionIndex,
                                 AS.getFnAttributes());
        FnAttrs.merge(B);
        AS = AS.addAttributes(Context, AttributeSet::FunctionIndex,
                              AttributeSet::get(Context,
                                                AttributeSet::FunctionIndex,
                                                FnAttrs));
        II->setAttributes(AS);
      } else {
        llvm_unreachable("invalid object with forward attribute group reference");
      }
    }
  
    // If there are entries in ForwardRefBlockAddresses at this point, the
    // function was never defined.
    if (!ForwardRefBlockAddresses.empty())
      return Error(ForwardRefBlockAddresses.begin()->first.Loc,
                   "expected function name in blockaddress");
  
    for (unsigned i = 0, e = NumberedTypes.size(); i != e; ++i)
      if (NumberedTypes[i].second.isValid())
        return Error(NumberedTypes[i].second,
                     "use of undefined type '%" + Twine(i) + "'");
  
    for (StringMap<std::pair<Type*, LocTy> >::iterator I =
         NamedTypes.begin(), E = NamedTypes.end(); I != E; ++I)
      if (I->second.second.isValid())
        return Error(I->second.second,
                     "use of undefined type named '" + I->getKey() + "'");
  
    if (!ForwardRefComdats.empty())
      return Error(ForwardRefComdats.begin()->second,
                   "use of undefined comdat '$" +
                       ForwardRefComdats.begin()->first + "'");
  
    if (!ForwardRefVals.empty())
      return Error(ForwardRefVals.begin()->second.second,
                   "use of undefined value '@" + ForwardRefVals.begin()->first +
                   "'");
  
    if (!ForwardRefValIDs.empty())
      return Error(ForwardRefValIDs.begin()->second.second,
                   "use of undefined value '@" +
                   Twine(ForwardRefValIDs.begin()->first) + "'");
  
    if (!ForwardRefMDNodes.empty())
      return Error(ForwardRefMDNodes.begin()->second.second,
                   "use of undefined metadata '!" +
                   Twine(ForwardRefMDNodes.begin()->first) + "'");
  
    // Resolve metadata cycles.
    for (auto &N : NumberedMetadata)
      if (auto *U = cast_or_null<UniquableMDNode>(N))
        U->resolveCycles();
  
    // Look for intrinsic functions and CallInst that need to be upgraded
    for (Module::iterator FI = M->begin(), FE = M->end(); FI != FE; )
      UpgradeCallsToIntrinsic(FI++); // must be post-increment, as we remove
  
    UpgradeDebugInfo(*M);
  
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Top-Level Entities
  //===----------------------------------------------------------------------===//
  
  bool LLParser::ParseTopLevelEntities() {
    while (1) {
      switch (Lex.getKind()) {
      default:         return TokError("expected top-level entity");
      case lltok::Eof: return false;
      case lltok::kw_declare: if (ParseDeclare()) return true; break;
      case lltok::kw_define:  if (ParseDefine()) return true; break;
      case lltok::kw_module:  if (ParseModuleAsm()) return true; break;
      case lltok::kw_target:  if (ParseTargetDefinition()) return true; break;
      case lltok::kw_deplibs: if (ParseDepLibs()) return true; break;
      case lltok::LocalVarID: if (ParseUnnamedType()) return true; break;
      case lltok::LocalVar:   if (ParseNamedType()) return true; break;
      case lltok::GlobalID:   if (ParseUnnamedGlobal()) return true; break;
      case lltok::GlobalVar:  if (ParseNamedGlobal()) return true; break;
      case lltok::ComdatVar:  if (parseComdat()) return true; break;
      case lltok::exclaim:    if (ParseStandaloneMetadata()) return true; break;
      case lltok::MetadataVar:if (ParseNamedMetadata()) return true; break;
  
      // The Global variable production with no name can have many different
      // optional leading prefixes, the production is:
      // GlobalVar ::= OptionalLinkage OptionalVisibility OptionalDLLStorageClass
      //               OptionalThreadLocal OptionalAddrSpace OptionalUnNammedAddr
      //               ('constant'|'global') ...
      case lltok::kw_private:             // OptionalLinkage
      case lltok::kw_internal:            // OptionalLinkage
      case lltok::kw_weak:                // OptionalLinkage
      case lltok::kw_weak_odr:            // OptionalLinkage
      case lltok::kw_linkonce:            // OptionalLinkage
      case lltok::kw_linkonce_odr:        // OptionalLinkage
      case lltok::kw_appending:           // OptionalLinkage
      case lltok::kw_common:              // OptionalLinkage
      case lltok::kw_extern_weak:         // OptionalLinkage
      case lltok::kw_external:            // OptionalLinkage
      case lltok::kw_default:             // OptionalVisibility
      case lltok::kw_hidden:              // OptionalVisibility
      case lltok::kw_protected:           // OptionalVisibility
      case lltok::kw_dllimport:           // OptionalDLLStorageClass
      case lltok::kw_dllexport:           // OptionalDLLStorageClass
      case lltok::kw_thread_local:        // OptionalThreadLocal
      case lltok::kw_addrspace:           // OptionalAddrSpace
      case lltok::kw_constant:            // GlobalType
      case lltok::kw_global: {            // GlobalType
        unsigned Linkage, Visibility, DLLStorageClass;
        bool UnnamedAddr;
        GlobalVariable::ThreadLocalMode TLM;
        bool HasLinkage;
        if (ParseOptionalLinkage(Linkage, HasLinkage) ||
            ParseOptionalVisibility(Visibility) ||
            ParseOptionalDLLStorageClass(DLLStorageClass) ||
            ParseOptionalThreadLocal(TLM) ||
            parseOptionalUnnamedAddr(UnnamedAddr) ||
            ParseGlobal("", SMLoc(), Linkage, HasLinkage, Visibility,
                        DLLStorageClass, TLM, UnnamedAddr))
          return true;
        break;
      }
  
      case lltok::kw_attributes: if (ParseUnnamedAttrGrp()) return true; break;
      case lltok::kw_uselistorder: if (ParseUseListOrder()) return true; break;
      case lltok::kw_uselistorder_bb:
                                   if (ParseUseListOrderBB()) return true; break;
      }
    }
  }
  
  
  /// toplevelentity
  ///   ::= 'module' 'asm' STRINGCONSTANT
  bool LLParser::ParseModuleAsm() {
    assert(Lex.getKind() == lltok::kw_module);
    Lex.Lex();
  
    std::string AsmStr;
    if (ParseToken(lltok::kw_asm, "expected 'module asm'") ||
        ParseStringConstant(AsmStr)) return true;
  
    M->appendModuleInlineAsm(AsmStr);
    return false;
  }
  
  /// toplevelentity
  ///   ::= 'target' 'triple' '=' STRINGCONSTANT
  ///   ::= 'target' 'datalayout' '=' STRINGCONSTANT
  bool LLParser::ParseTargetDefinition() {
    assert(Lex.getKind() == lltok::kw_target);
    std::string Str;
    switch (Lex.Lex()) {
    default: return TokError("unknown target property");
    case lltok::kw_triple:
      Lex.Lex();
      if (ParseToken(lltok::equal, "expected '=' after target triple") ||
          ParseStringConstant(Str))
        return true;
      M->setTargetTriple(Str);
      return false;
    case lltok::kw_datalayout:
      Lex.Lex();
      if (ParseToken(lltok::equal, "expected '=' after target datalayout") ||
          ParseStringConstant(Str))
        return true;
      M->setDataLayout(Str);
      return false;
    }
  }
  
  /// toplevelentity
  ///   ::= 'deplibs' '=' '[' ']'
  ///   ::= 'deplibs' '=' '[' STRINGCONSTANT (',' STRINGCONSTANT)* ']'
  /// FIXME: Remove in 4.0. Currently parse, but ignore.
  bool LLParser::ParseDepLibs() {
    assert(Lex.getKind() == lltok::kw_deplibs);
    Lex.Lex();
    if (ParseToken(lltok::equal, "expected '=' after deplibs") ||
        ParseToken(lltok::lsquare, "expected '=' after deplibs"))
      return true;
  
    if (EatIfPresent(lltok::rsquare))
      return false;
  
    do {
      std::string Str;
      if (ParseStringConstant(Str)) return true;
    } while (EatIfPresent(lltok::comma));
  
    return ParseToken(lltok::rsquare, "expected ']' at end of list");
  }
  
  /// ParseUnnamedType:
  ///   ::= LocalVarID '=' 'type' type
  bool LLParser::ParseUnnamedType() {
    LocTy TypeLoc = Lex.getLoc();
    unsigned TypeID = Lex.getUIntVal();
    Lex.Lex(); // eat LocalVarID;
  
    if (ParseToken(lltok::equal, "expected '=' after name") ||
        ParseToken(lltok::kw_type, "expected 'type' after '='"))
      return true;
  
    if (TypeID >= NumberedTypes.size())
      NumberedTypes.resize(TypeID+1);
  
    Type *Result = nullptr;
    if (ParseStructDefinition(TypeLoc, "",
                              NumberedTypes[TypeID], Result)) return true;
  
    if (!isa<StructType>(Result)) {
      std::pair<Type*, LocTy> &Entry = NumberedTypes[TypeID];
      if (Entry.first)
        return Error(TypeLoc, "non-struct types may not be recursive");
      Entry.first = Result;
      Entry.second = SMLoc();
    }
  
    return false;
  }
  
  
  /// toplevelentity
  ///   ::= LocalVar '=' 'type' type
  bool LLParser::ParseNamedType() {
    std::string Name = Lex.getStrVal();
    LocTy NameLoc = Lex.getLoc();
    Lex.Lex();  // eat LocalVar.
  
    if (ParseToken(lltok::equal, "expected '=' after name") ||
        ParseToken(lltok::kw_type, "expected 'type' after name"))
      return true;
  
    Type *Result = nullptr;
    if (ParseStructDefinition(NameLoc, Name,
                              NamedTypes[Name], Result)) return true;
  
    if (!isa<StructType>(Result)) {
      std::pair<Type*, LocTy> &Entry = NamedTypes[Name];
      if (Entry.first)
        return Error(NameLoc, "non-struct types may not be recursive");
      Entry.first = Result;
      Entry.second = SMLoc();
    }
  
    return false;
  }
  
  
  /// toplevelentity
  ///   ::= 'declare' FunctionHeader
  bool LLParser::ParseDeclare() {
    assert(Lex.getKind() == lltok::kw_declare);
    Lex.Lex();
  
    Function *F;
    return ParseFunctionHeader(F, false);
  }
  
  /// toplevelentity
  ///   ::= 'define' FunctionHeader '{' ...
  bool LLParser::ParseDefine() {
    assert(Lex.getKind() == lltok::kw_define);
    Lex.Lex();
  
    Function *F;
    return ParseFunctionHeader(F, true) ||
           ParseFunctionBody(*F);
  }
  
  /// ParseGlobalType
  ///   ::= 'constant'
  ///   ::= 'global'
  bool LLParser::ParseGlobalType(bool &IsConstant) {
    if (Lex.getKind() == lltok::kw_constant)
      IsConstant = true;
    else if (Lex.getKind() == lltok::kw_global)
      IsConstant = false;
    else {
      IsConstant = false;
      return TokError("expected 'global' or 'constant'");
    }
    Lex.Lex();
    return false;
  }
  
  /// ParseUnnamedGlobal:
  ///   OptionalVisibility ALIAS ...
  ///   OptionalLinkage OptionalVisibility OptionalDLLStorageClass
  ///                                                     ...   -> global variable
  ///   GlobalID '=' OptionalVisibility ALIAS ...
  ///   GlobalID '=' OptionalLinkage OptionalVisibility OptionalDLLStorageClass
  ///                                                     ...   -> global variable
  bool LLParser::ParseUnnamedGlobal() {
    unsigned VarID = NumberedVals.size();
    std::string Name;
    LocTy NameLoc = Lex.getLoc();
  
    // Handle the GlobalID form.
    if (Lex.getKind() == lltok::GlobalID) {
      if (Lex.getUIntVal() != VarID)
        return Error(Lex.getLoc(), "variable expected to be numbered '%" +
                     Twine(VarID) + "'");
      Lex.Lex(); // eat GlobalID;
  
      if (ParseToken(lltok::equal, "expected '=' after name"))
        return true;
    }
  
    bool HasLinkage;
    unsigned Linkage, Visibility, DLLStorageClass;
    GlobalVariable::ThreadLocalMode TLM;
    bool UnnamedAddr;
    if (ParseOptionalLinkage(Linkage, HasLinkage) ||
        ParseOptionalVisibility(Visibility) ||
        ParseOptionalDLLStorageClass(DLLStorageClass) ||
        ParseOptionalThreadLocal(TLM) ||
        parseOptionalUnnamedAddr(UnnamedAddr))
      return true;
  
    if (Lex.getKind() != lltok::kw_alias)
      return ParseGlobal(Name, NameLoc, Linkage, HasLinkage, Visibility,
                         DLLStorageClass, TLM, UnnamedAddr);
    return ParseAlias(Name, NameLoc, Linkage, Visibility, DLLStorageClass, TLM,
                      UnnamedAddr);
  }
  
  /// ParseNamedGlobal:
  ///   GlobalVar '=' OptionalVisibility ALIAS ...
  ///   GlobalVar '=' OptionalLinkage OptionalVisibility OptionalDLLStorageClass
  ///                                                     ...   -> global variable
  bool LLParser::ParseNamedGlobal() {
    assert(Lex.getKind() == lltok::GlobalVar);
    LocTy NameLoc = Lex.getLoc();
    std::string Name = Lex.getStrVal();
    Lex.Lex();
  
    bool HasLinkage;
    unsigned Linkage, Visibility, DLLStorageClass;
    GlobalVariable::ThreadLocalMode TLM;
    bool UnnamedAddr;
    if (ParseToken(lltok::equal, "expected '=' in global variable") ||
        ParseOptionalLinkage(Linkage, HasLinkage) ||
        ParseOptionalVisibility(Visibility) ||
        ParseOptionalDLLStorageClass(DLLStorageClass) ||
        ParseOptionalThreadLocal(TLM) ||
        parseOptionalUnnamedAddr(UnnamedAddr))
      return true;
  
    if (Lex.getKind() != lltok::kw_alias)
      return ParseGlobal(Name, NameLoc, Linkage, HasLinkage, Visibility,
                         DLLStorageClass, TLM, UnnamedAddr);
  
    return ParseAlias(Name, NameLoc, Linkage, Visibility, DLLStorageClass, TLM,
                      UnnamedAddr);
  }
  
  bool LLParser::parseComdat() {
    assert(Lex.getKind() == lltok::ComdatVar);
    std::string Name = Lex.getStrVal();
    LocTy NameLoc = Lex.getLoc();
    Lex.Lex();
  
    if (ParseToken(lltok::equal, "expected '=' here"))
      return true;
  
    if (ParseToken(lltok::kw_comdat, "expected comdat keyword"))
      return TokError("expected comdat type");
  
    Comdat::SelectionKind SK;
    switch (Lex.getKind()) {
    default:
      return TokError("unknown selection kind");
    case lltok::kw_any:
      SK = Comdat::Any;
      break;
    case lltok::kw_exactmatch:
      SK = Comdat::ExactMatch;
      break;
    case lltok::kw_largest:
      SK = Comdat::Largest;
      break;
    case lltok::kw_noduplicates:
      SK = Comdat::NoDuplicates;
      break;
    case lltok::kw_samesize:
      SK = Comdat::SameSize;
      break;
    }
    Lex.Lex();
  
    // See if the comdat was forward referenced, if so, use the comdat.
    Module::ComdatSymTabType &ComdatSymTab = M->getComdatSymbolTable();
    Module::ComdatSymTabType::iterator I = ComdatSymTab.find(Name);
    if (I != ComdatSymTab.end() && !ForwardRefComdats.erase(Name))
      return Error(NameLoc, "redefinition of comdat '$" + Name + "'");
  
    Comdat *C;
    if (I != ComdatSymTab.end())
      C = &I->second;
    else
      C = M->getOrInsertComdat(Name);
    C->setSelectionKind(SK);
  
    return false;
  }
  
  // MDString:
  //   ::= '!' STRINGCONSTANT
  bool LLParser::ParseMDString(MDString *&Result) {
    std::string Str;
    if (ParseStringConstant(Str)) return true;
    llvm::UpgradeMDStringConstant(Str);
    Result = MDString::get(Context, Str);
    return false;
  }
  
  // MDNode:
  //   ::= '!' MDNodeNumber
  bool LLParser::ParseMDNodeID(MDNode *&Result) {
    // !{ ..., !42, ... }
    unsigned MID = 0;
    if (ParseUInt32(MID))
      return true;
  
    // If not a forward reference, just return it now.
    if (MID < NumberedMetadata.size() && NumberedMetadata[MID] != nullptr) {
      Result = NumberedMetadata[MID];
      return false;
    }
  
    // Otherwise, create MDNode forward reference.
    MDNodeFwdDecl *FwdNode = MDNodeFwdDecl::get(Context, None);
    ForwardRefMDNodes[MID] = std::make_pair(FwdNode, Lex.getLoc());
  
    if (NumberedMetadata.size() <= MID)
      NumberedMetadata.resize(MID+1);
    NumberedMetadata[MID].reset(FwdNode);
    Result = FwdNode;
    return false;
  }
  
  /// ParseNamedMetadata:
  ///   !foo = !{ !1, !2 }
  bool LLParser::ParseNamedMetadata() {
    assert(Lex.getKind() == lltok::MetadataVar);
    std::string Name = Lex.getStrVal();
    Lex.Lex();
  
    if (ParseToken(lltok::equal, "expected '=' here") ||
        ParseToken(lltok::exclaim, "Expected '!' here") ||
        ParseToken(lltok::lbrace, "Expected '{' here"))
      return true;
  
    NamedMDNode *NMD = M->getOrInsertNamedMetadata(Name);
    if (Lex.getKind() != lltok::rbrace)
      do {
        if (ParseToken(lltok::exclaim, "Expected '!' here"))
          return true;
  
        MDNode *N = nullptr;
        if (ParseMDNodeID(N)) return true;
        NMD->addOperand(N);
      } while (EatIfPresent(lltok::comma));
  
    if (ParseToken(lltok::rbrace, "expected end of metadata node"))
      return true;
  
    return false;
  }
  
  /// ParseStandaloneMetadata:
  ///   !42 = !{...}
  bool LLParser::ParseStandaloneMetadata() {
    assert(Lex.getKind() == lltok::exclaim);
    Lex.Lex();
    unsigned MetadataID = 0;
  
    MDNode *Init;
    if (ParseUInt32(MetadataID) ||
        ParseToken(lltok::equal, "expected '=' here"))
      return true;
  
    // Detect common error, from old metadata syntax.
    if (Lex.getKind() == lltok::Type)
      return TokError("unexpected type in metadata definition");
  
    bool IsDistinct = EatIfPresent(lltok::kw_distinct);
    if (Lex.getKind() == lltok::MetadataVar) {
      if (ParseSpecializedMDNode(Init, IsDistinct))
        return true;
    } else if (ParseToken(lltok::exclaim, "Expected '!' here") ||
               ParseMDTuple(Init, IsDistinct))
      return true;
  
    // See if this was forward referenced, if so, handle it.
    auto FI = ForwardRefMDNodes.find(MetadataID);
    if (FI != ForwardRefMDNodes.end()) {
      MDNodeFwdDecl *Temp = FI->second.first;
      Temp->replaceAllUsesWith(Init);
      delete Temp;
      ForwardRefMDNodes.erase(FI);
  
      assert(NumberedMetadata[MetadataID] == Init && "Tracking VH didn't work");
    } else {
      if (MetadataID >= NumberedMetadata.size())
        NumberedMetadata.resize(MetadataID+1);
  
      if (NumberedMetadata[MetadataID] != nullptr)
        return TokError("Metadata id is already used");
      NumberedMetadata[MetadataID].reset(Init);
    }
  
    return false;
  }
  
  static bool isValidVisibilityForLinkage(unsigned V, unsigned L) {
    return !GlobalValue::isLocalLinkage((GlobalValue::LinkageTypes)L) ||
           (GlobalValue::VisibilityTypes)V == GlobalValue::DefaultVisibility;
  }
  
  /// ParseAlias:
  ///   ::= GlobalVar '=' OptionalLinkage OptionalVisibility
  ///                     OptionalDLLStorageClass OptionalThreadLocal
  ///                     OptionalUnNammedAddr 'alias' Aliasee
  ///
  /// Aliasee
  ///   ::= TypeAndValue
  ///
  /// Everything through OptionalUnNammedAddr has already been parsed.
  ///
  bool LLParser::ParseAlias(const std::string &Name, LocTy NameLoc, unsigned L,
                            unsigned Visibility, unsigned DLLStorageClass,
                            GlobalVariable::ThreadLocalMode TLM,
                            bool UnnamedAddr) {
    assert(Lex.getKind() == lltok::kw_alias);
    Lex.Lex();
  
    GlobalValue::LinkageTypes Linkage = (GlobalValue::LinkageTypes) L;
  
    if(!GlobalAlias::isValidLinkage(Linkage))
      return Error(NameLoc, "invalid linkage type for alias");
  
    if (!isValidVisibilityForLinkage(Visibility, L))
      return Error(NameLoc,
                   "symbol with local linkage must have default visibility");
  
    Constant *Aliasee;
    LocTy AliaseeLoc = Lex.getLoc();
    if (Lex.getKind() != lltok::kw_bitcast &&
        Lex.getKind() != lltok::kw_getelementptr &&
        Lex.getKind() != lltok::kw_addrspacecast &&
        Lex.getKind() != lltok::kw_inttoptr) {
      if (ParseGlobalTypeAndValue(Aliasee))
        return true;
    } else {
      // The bitcast dest type is not present, it is implied by the dest type.
      ValID ID;
      if (ParseValID(ID))
        return true;
      if (ID.Kind != ValID::t_Constant)
        return Error(AliaseeLoc, "invalid aliasee");
      Aliasee = ID.ConstantVal;
    }
  
    Type *AliaseeType = Aliasee->getType();
    auto *PTy = dyn_cast<PointerType>(AliaseeType);
    if (!PTy)
      return Error(AliaseeLoc, "An alias must have pointer type");
    Type *Ty = PTy->getElementType();
    unsigned AddrSpace = PTy->getAddressSpace();
  
    // Okay, create the alias but do not insert it into the module yet.
    std::unique_ptr<GlobalAlias> GA(
        GlobalAlias::create(Ty, AddrSpace, (GlobalValue::LinkageTypes)Linkage,
                            Name, Aliasee, /*Parent*/ nullptr));
    GA->setThreadLocalMode(TLM);
    GA->setVisibility((GlobalValue::VisibilityTypes)Visibility);
    GA->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
    GA->setUnnamedAddr(UnnamedAddr);
  
    // See if this value already exists in the symbol table.  If so, it is either
    // a redefinition or a definition of a forward reference.
    if (GlobalValue *Val = M->getNamedValue(Name)) {
      // See if this was a redefinition.  If so, there is no entry in
      // ForwardRefVals.
      std::map<std::string, std::pair<GlobalValue*, LocTy> >::iterator
        I = ForwardRefVals.find(Name);
      if (I == ForwardRefVals.end())
        return Error(NameLoc, "redefinition of global named '@" + Name + "'");
  
      // Otherwise, this was a definition of forward ref.  Verify that types
      // agree.
      if (Val->getType() != GA->getType())
        return Error(NameLoc,
                "forward reference and definition of alias have different types");
  
      // If they agree, just RAUW the old value with the alias and remove the
      // forward ref info.
      Val->replaceAllUsesWith(GA.get());
      Val->eraseFromParent();
      ForwardRefVals.erase(I);
    }
  
    // Insert into the module, we know its name won't collide now.
    M->getAliasList().push_back(GA.get());
    assert(GA->getName() == Name && "Should not be a name conflict!");
  
    // The module owns this now
    GA.release();
  
    return false;
  }
  
  /// ParseGlobal
  ///   ::= GlobalVar '=' OptionalLinkage OptionalVisibility OptionalDLLStorageClass
  ///       OptionalThreadLocal OptionalUnNammedAddr OptionalAddrSpace
  ///       OptionalExternallyInitialized GlobalType Type Const
  ///   ::= OptionalLinkage OptionalVisibility OptionalDLLStorageClass
  ///       OptionalThreadLocal OptionalUnNammedAddr OptionalAddrSpace
  ///       OptionalExternallyInitialized GlobalType Type Const
  ///
  /// Everything up to and including OptionalUnNammedAddr has been parsed
  /// already.
  ///
  bool LLParser::ParseGlobal(const std::string &Name, LocTy NameLoc,
                             unsigned Linkage, bool HasLinkage,
                             unsigned Visibility, unsigned DLLStorageClass,
                             GlobalVariable::ThreadLocalMode TLM,
                             bool UnnamedAddr) {
    if (!isValidVisibilityForLinkage(Visibility, Linkage))
      return Error(NameLoc,
                   "symbol with local linkage must have default visibility");
  
    unsigned AddrSpace;
    bool IsConstant, IsExternallyInitialized;
    LocTy IsExternallyInitializedLoc;
    LocTy TyLoc;
  
    Type *Ty = nullptr;
    if (ParseOptionalAddrSpace(AddrSpace) ||
        ParseOptionalToken(lltok::kw_externally_initialized,
                           IsExternallyInitialized,
                           &IsExternallyInitializedLoc) ||
        ParseGlobalType(IsConstant) ||
        ParseType(Ty, TyLoc))
      return true;
  
    // If the linkage is specified and is external, then no initializer is
    // present.
    Constant *Init = nullptr;
    if (!HasLinkage || (Linkage != GlobalValue::ExternalWeakLinkage &&
                        Linkage != GlobalValue::ExternalLinkage)) {
      if (ParseGlobalValue(Ty, Init))
        return true;
    }
  
    if (Ty->isFunctionTy() || Ty->isLabelTy())
      return Error(TyLoc, "invalid type for global variable");
  
    GlobalValue *GVal = nullptr;
  
    // See if the global was forward referenced, if so, use the global.
    if (!Name.empty()) {
      GVal = M->getNamedValue(Name);
      if (GVal) {
        if (!ForwardRefVals.erase(Name) || !isa<GlobalValue>(GVal))
          return Error(NameLoc, "redefinition of global '@" + Name + "'");
      }
    } else {
      std::map<unsigned, std::pair<GlobalValue*, LocTy> >::iterator
        I = ForwardRefValIDs.find(NumberedVals.size());
      if (I != ForwardRefValIDs.end()) {
        GVal = I->second.first;
        ForwardRefValIDs.erase(I);
      }
    }
  
    GlobalVariable *GV;
    if (!GVal) {
      GV = new GlobalVariable(*M, Ty, false, GlobalValue::ExternalLinkage, nullptr,
                              Name, nullptr, GlobalVariable::NotThreadLocal,
                              AddrSpace);
    } else {
      if (GVal->getType()->getElementType() != Ty)
        return Error(TyLoc,
              "forward reference and definition of global have different types");
  
      GV = cast<GlobalVariable>(GVal);
  
      // Move the forward-reference to the correct spot in the module.
      M->getGlobalList().splice(M->global_end(), M->getGlobalList(), GV);
    }
  
    if (Name.empty())
      NumberedVals.push_back(GV);
  
    // Set the parsed properties on the global.
    if (Init)
      GV->setInitializer(Init);
    GV->setConstant(IsConstant);
    GV->setLinkage((GlobalValue::LinkageTypes)Linkage);
    GV->setVisibility((GlobalValue::VisibilityTypes)Visibility);
    GV->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
    GV->setExternallyInitialized(IsExternallyInitialized);
    GV->setThreadLocalMode(TLM);
    GV->setUnnamedAddr(UnnamedAddr);
  
    // Parse attributes on the global.
    while (Lex.getKind() == lltok::comma) {
      Lex.Lex();
  
      if (Lex.getKind() == lltok::kw_section) {
        Lex.Lex();
        GV->setSection(Lex.getStrVal());
        if (ParseToken(lltok::StringConstant, "expected global section string"))
          return true;
      } else if (Lex.getKind() == lltok::kw_align) {
        unsigned Alignment;
        if (ParseOptionalAlignment(Alignment)) return true;
        GV->setAlignment(Alignment);
      } else {
        Comdat *C;
        if (parseOptionalComdat(Name, C))
          return true;
        if (C)
          GV->setComdat(C);
        else
          return TokError("unknown global variable property!");
      }
    }
  
    return false;
  }
  
  /// ParseUnnamedAttrGrp
  ///   ::= 'attributes' AttrGrpID '=' '{' AttrValPair+ '}'
  bool LLParser::ParseUnnamedAttrGrp() {
    assert(Lex.getKind() == lltok::kw_attributes);
    LocTy AttrGrpLoc = Lex.getLoc();
    Lex.Lex();
  
    if (Lex.getKind() != lltok::AttrGrpID)
      return TokError("expected attribute group id");
  
    unsigned VarID = Lex.getUIntVal();
    std::vector<unsigned> unused;
    LocTy BuiltinLoc;
    Lex.Lex();
  
    if (ParseToken(lltok::equal, "expected '=' here") ||
        ParseToken(lltok::lbrace, "expected '{' here") ||
        ParseFnAttributeValuePairs(NumberedAttrBuilders[VarID], unused, true,
                                   BuiltinLoc) ||
        ParseToken(lltok::rbrace, "expected end of attribute group"))
      return true;
  
    if (!NumberedAttrBuilders[VarID].hasAttributes())
      return Error(AttrGrpLoc, "attribute group has no attributes");
  
    return false;
  }
  
  /// ParseFnAttributeValuePairs
  ///   ::= <attr> | <attr> '=' <value>
  bool LLParser::ParseFnAttributeValuePairs(AttrBuilder &B,
                                            std::vector<unsigned> &FwdRefAttrGrps,
                                            bool inAttrGrp, LocTy &BuiltinLoc) {
    bool HaveError = false;
  
    B.clear();
  
    while (true) {
      lltok::Kind Token = Lex.getKind();
      if (Token == lltok::kw_builtin)
        BuiltinLoc = Lex.getLoc();
      switch (Token) {
      default:
        if (!inAttrGrp) return HaveError;
        return Error(Lex.getLoc(), "unterminated attribute group");
      case lltok::rbrace:
        // Finished.
        return false;
  
      case lltok::AttrGrpID: {
        // Allow a function to reference an attribute group:
        //
        //   define void @foo() #1 { ... }
        if (inAttrGrp)
          HaveError |=
            Error(Lex.getLoc(),
                "cannot have an attribute group reference in an attribute group");
  
        unsigned AttrGrpNum = Lex.getUIntVal();
        if (inAttrGrp) break;
  
        // Save the reference to the attribute group. We'll fill it in later.
        FwdRefAttrGrps.push_back(AttrGrpNum);
        break;
      }
      // Target-dependent attributes:
      case lltok::StringConstant: {
        std::string Attr = Lex.getStrVal();
        Lex.Lex();
        std::string Val;
        if (EatIfPresent(lltok::equal) &&
            ParseStringConstant(Val))
          return true;
  
        B.addAttribute(Attr, Val);
        continue;
      }
  
      // Target-independent attributes:
      case lltok::kw_align: {
        // As a hack, we allow function alignment to be initially parsed as an
        // attribute on a function declaration/definition or added to an attribute
        // group and later moved to the alignment field.
        unsigned Alignment;
        if (inAttrGrp) {
          Lex.Lex();
          if (ParseToken(lltok::equal, "expected '=' here") ||
              ParseUInt32(Alignment))
            return true;
        } else {
          if (ParseOptionalAlignment(Alignment))
            return true;
        }
        B.addAlignmentAttr(Alignment);
        continue;
      }
      case lltok::kw_alignstack: {
        unsigned Alignment;
        if (inAttrGrp) {
          Lex.Lex();
          if (ParseToken(lltok::equal, "expected '=' here") ||
              ParseUInt32(Alignment))
            return true;
        } else {
          if (ParseOptionalStackAlignment(Alignment))
            return true;
        }
        B.addStackAlignmentAttr(Alignment);
        continue;
      }
      case lltok::kw_alwaysinline:      B.addAttribute(Attribute::AlwaysInline); break;
      case lltok::kw_builtin:           B.addAttribute(Attribute::Builtin); break;
      case lltok::kw_cold:              B.addAttribute(Attribute::Cold); break;
      case lltok::kw_inlinehint:        B.addAttribute(Attribute::InlineHint); break;
      case lltok::kw_jumptable:         B.addAttribute(Attribute::JumpTable); break;
      case lltok::kw_minsize:           B.addAttribute(Attribute::MinSize); break;
      case lltok::kw_naked:             B.addAttribute(Attribute::Naked); break;
      case lltok::kw_nobuiltin:         B.addAttribute(Attribute::NoBuiltin); break;
      case lltok::kw_noduplicate:       B.addAttribute(Attribute::NoDuplicate); break;
      case lltok::kw_noimplicitfloat:   B.addAttribute(Attribute::NoImplicitFloat); break;
      case lltok::kw_noinline:          B.addAttribute(Attribute::NoInline); break;
      case lltok::kw_nonlazybind:       B.addAttribute(Attribute::NonLazyBind); break;
      case lltok::kw_noredzone:         B.addAttribute(Attribute::NoRedZone); break;
      case lltok::kw_noreturn:          B.addAttribute(Attribute::NoReturn); break;
      case lltok::kw_nounwind:          B.addAttribute(Attribute::NoUnwind); break;
      case lltok::kw_optnone:           B.addAttribute(Attribute::OptimizeNone); break;
      case lltok::kw_optsize:           B.addAttribute(Attribute::OptimizeForSize); break;
      case lltok::kw_readnone:          B.addAttribute(Attribute::ReadNone); break;
      case lltok::kw_readonly:          B.addAttribute(Attribute::ReadOnly); break;
      case lltok::kw_returns_twice:     B.addAttribute(Attribute::ReturnsTwice); break;
      case lltok::kw_ssp:               B.addAttribute(Attribute::StackProtect); break;
      case lltok::kw_sspreq:            B.addAttribute(Attribute::StackProtectReq); break;
      case lltok::kw_sspstrong:         B.addAttribute(Attribute::StackProtectStrong); break;
      case lltok::kw_sanitize_address:  B.addAttribute(Attribute::SanitizeAddress); break;
      case lltok::kw_sanitize_thread:   B.addAttribute(Attribute::SanitizeThread); break;
      case lltok::kw_sanitize_memory:   B.addAttribute(Attribute::SanitizeMemory); break;
      case lltok::kw_uwtable:           B.addAttribute(Attribute::UWTable); break;
  
      // Error handling.
      case lltok::kw_inreg:
      case lltok::kw_signext:
      case lltok::kw_zeroext:
        HaveError |=
          Error(Lex.getLoc(),
                "invalid use of attribute on a function");
        break;
      case lltok::kw_byval:
      case lltok::kw_dereferenceable:
      case lltok::kw_inalloca:
      case lltok::kw_nest:
      case lltok::kw_noalias:
      case lltok::kw_nocapture:
      case lltok::kw_nonnull:
      case lltok::kw_returned:
      case lltok::kw_sret:
        HaveError |=
          Error(Lex.getLoc(),
                "invalid use of parameter-only attribute on a function");
        break;
      }
  
      Lex.Lex();
    }
  }
  
  //===----------------------------------------------------------------------===//
  // GlobalValue Reference/Resolution Routines.
  //===----------------------------------------------------------------------===//
  
  /// GetGlobalVal - Get a value with the specified name or ID, creating a
  /// forward reference record if needed.  This can return null if the value
  /// exists but does not have the right type.
  GlobalValue *LLParser::GetGlobalVal(const std::string &Name, Type *Ty,
                                      LocTy Loc) {
    PointerType *PTy = dyn_cast<PointerType>(Ty);
    if (!PTy) {
      Error(Loc, "global variable reference must have pointer type");
      return nullptr;
    }
  
    // Look this name up in the normal function symbol table.
    GlobalValue *Val =
      cast_or_null<GlobalValue>(M->getValueSymbolTable().lookup(Name));
  
    // If this is a forward reference for the value, see if we already created a
    // forward ref record.
    if (!Val) {
      std::map<std::string, std::pair<GlobalValue*, LocTy> >::iterator
        I = ForwardRefVals.find(Name);
      if (I != ForwardRefVals.end())
        Val = I->second.first;
    }
  
    // If we have the value in the symbol table or fwd-ref table, return it.
    if (Val) {
      if (Val->getType() == Ty) return Val;
      Error(Loc, "'@" + Name + "' defined with type '" +
            getTypeString(Val->getType()) + "'");
      return nullptr;
    }
  
    // Otherwise, create a new forward reference for this value and remember it.
    GlobalValue *FwdVal;
    if (FunctionType *FT = dyn_cast<FunctionType>(PTy->getElementType()))
      FwdVal = Function::Create(FT, GlobalValue::ExternalWeakLinkage, Name, M);
    else
      FwdVal = new GlobalVariable(*M, PTy->getElementType(), false,
                                  GlobalValue::ExternalWeakLinkage, nullptr, Name,
                                  nullptr, GlobalVariable::NotThreadLocal,
                                  PTy->getAddressSpace());
  
    ForwardRefVals[Name] = std::make_pair(FwdVal, Loc);
    return FwdVal;
  }
  
  GlobalValue *LLParser::GetGlobalVal(unsigned ID, Type *Ty, LocTy Loc) {
    PointerType *PTy = dyn_cast<PointerType>(Ty);
    if (!PTy) {
      Error(Loc, "global variable reference must have pointer type");
      return nullptr;
    }
  
    GlobalValue *Val = ID < NumberedVals.size() ? NumberedVals[ID] : nullptr;
  
    // If this is a forward reference for the value, see if we already created a
    // forward ref record.
    if (!Val) {
      std::map<unsigned, std::pair<GlobalValue*, LocTy> >::iterator
        I = ForwardRefValIDs.find(ID);
      if (I != ForwardRefValIDs.end())
        Val = I->second.first;
    }
  
    // If we have the value in the symbol table or fwd-ref table, return it.
    if (Val) {
      if (Val->getType() == Ty) return Val;
      Error(Loc, "'@" + Twine(ID) + "' defined with type '" +
            getTypeString(Val->getType()) + "'");
      return nullptr;
    }
  
    // Otherwise, create a new forward reference for this value and remember it.
    GlobalValue *FwdVal;
    if (FunctionType *FT = dyn_cast<FunctionType>(PTy->getElementType()))
      FwdVal = Function::Create(FT, GlobalValue::ExternalWeakLinkage, "", M);
    else
      FwdVal = new GlobalVariable(*M, PTy->getElementType(), false,
                                  GlobalValue::ExternalWeakLinkage, nullptr, "");
  
    ForwardRefValIDs[ID] = std::make_pair(FwdVal, Loc);
    return FwdVal;
  }
  
  
  //===----------------------------------------------------------------------===//
  // Comdat Reference/Resolution Routines.
  //===----------------------------------------------------------------------===//
  
  Comdat *LLParser::getComdat(const std::string &Name, LocTy Loc) {
    // Look this name up in the comdat symbol table.
    Module::ComdatSymTabType &ComdatSymTab = M->getComdatSymbolTable();
    Module::ComdatSymTabType::iterator I = ComdatSymTab.find(Name);
    if (I != ComdatSymTab.end())
      return &I->second;
  
    // Otherwise, create a new forward reference for this value and remember it.
    Comdat *C = M->getOrInsertComdat(Name);
    ForwardRefComdats[Name] = Loc;
    return C;
  }
  
  
  //===----------------------------------------------------------------------===//
  // Helper Routines.
  //===----------------------------------------------------------------------===//
  
  /// ParseToken - If the current token has the specified kind, eat it and return
  /// success.  Otherwise, emit the specified error and return failure.
  bool LLParser::ParseToken(lltok::Kind T, const char *ErrMsg) {
    if (Lex.getKind() != T)
      return TokError(ErrMsg);
    Lex.Lex();
    return false;
  }
  
  /// ParseStringConstant
  ///   ::= StringConstant
  bool LLParser::ParseStringConstant(std::string &Result) {
    if (Lex.getKind() != lltok::StringConstant)
      return TokError("expected string constant");
    Result = Lex.getStrVal();
    Lex.Lex();
    return false;
  }
  
  /// ParseUInt32
  ///   ::= uint32
  bool LLParser::ParseUInt32(unsigned &Val) {
    if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
      return TokError("expected integer");
    uint64_t Val64 = Lex.getAPSIntVal().getLimitedValue(0xFFFFFFFFULL+1);
    if (Val64 != unsigned(Val64))
      return TokError("expected 32-bit integer (too large)");
    Val = Val64;
    Lex.Lex();
    return false;
  }
  
  /// ParseUInt64
  ///   ::= uint64
  bool LLParser::ParseUInt64(uint64_t &Val) {
    if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
      return TokError("expected integer");
    Val = Lex.getAPSIntVal().getLimitedValue();
    Lex.Lex();
    return false;
  }
  
  /// ParseTLSModel
  ///   := 'localdynamic'
  ///   := 'initialexec'
  ///   := 'localexec'
  bool LLParser::ParseTLSModel(GlobalVariable::ThreadLocalMode &TLM) {
    switch (Lex.getKind()) {
      default:
        return TokError("expected localdynamic, initialexec or localexec");
      case lltok::kw_localdynamic:
        TLM = GlobalVariable::LocalDynamicTLSModel;
        break;
      case lltok::kw_initialexec:
        TLM = GlobalVariable::InitialExecTLSModel;
        break;
      case lltok::kw_localexec:
        TLM = GlobalVariable::LocalExecTLSModel;
        break;
    }
  
    Lex.Lex();
    return false;
  }
  
  /// ParseOptionalThreadLocal
  ///   := /*empty*/
  ///   := 'thread_local'
  ///   := 'thread_local' '(' tlsmodel ')'
  bool LLParser::ParseOptionalThreadLocal(GlobalVariable::ThreadLocalMode &TLM) {
    TLM = GlobalVariable::NotThreadLocal;
    if (!EatIfPresent(lltok::kw_thread_local))
      return false;
  
    TLM = GlobalVariable::GeneralDynamicTLSModel;
    if (Lex.getKind() == lltok::lparen) {
      Lex.Lex();
      return ParseTLSModel(TLM) ||
        ParseToken(lltok::rparen, "expected ')' after thread local model");
    }
    return false;
  }
  
  /// ParseOptionalAddrSpace
  ///   := /*empty*/
  ///   := 'addrspace' '(' uint32 ')'
  bool LLParser::ParseOptionalAddrSpace(unsigned &AddrSpace) {
    AddrSpace = 0;
    if (!EatIfPresent(lltok::kw_addrspace))
      return false;
    return ParseToken(lltok::lparen, "expected '(' in address space") ||
           ParseUInt32(AddrSpace) ||
           ParseToken(lltok::rparen, "expected ')' in address space");
  }
  
  /// ParseOptionalParamAttrs - Parse a potentially empty list of parameter attributes.
  bool LLParser::ParseOptionalParamAttrs(AttrBuilder &B) {
    bool HaveError = false;
  
    B.clear();
  
    while (1) {
      lltok::Kind Token = Lex.getKind();
      switch (Token) {
      default:  // End of attributes.
        return HaveError;
      case lltok::kw_align: {
        unsigned Alignment;
        if (ParseOptionalAlignment(Alignment))
          return true;
        B.addAlignmentAttr(Alignment);
        continue;
      }
      case lltok::kw_byval:           B.addAttribute(Attribute::ByVal); break;
      case lltok::kw_dereferenceable: {
        uint64_t Bytes;
        if (ParseOptionalDereferenceableBytes(Bytes))
          return true;
        B.addDereferenceableAttr(Bytes);
        continue;
      }
      case lltok::kw_inalloca:        B.addAttribute(Attribute::InAlloca); break;
      case lltok::kw_inreg:           B.addAttribute(Attribute::InReg); break;
      case lltok::kw_nest:            B.addAttribute(Attribute::Nest); break;
      case lltok::kw_noalias:         B.addAttribute(Attribute::NoAlias); break;
      case lltok::kw_nocapture:       B.addAttribute(Attribute::NoCapture); break;
      case lltok::kw_nonnull:         B.addAttribute(Attribute::NonNull); break;
      case lltok::kw_readnone:        B.addAttribute(Attribute::ReadNone); break;
      case lltok::kw_readonly:        B.addAttribute(Attribute::ReadOnly); break;
      case lltok::kw_returned:        B.addAttribute(Attribute::Returned); break;
      case lltok::kw_signext:         B.addAttribute(Attribute::SExt); break;
      case lltok::kw_sret:            B.addAttribute(Attribute::StructRet); break;
      case lltok::kw_zeroext:         B.addAttribute(Attribute::ZExt); break;
  
      case lltok::kw_alignstack:
      case lltok::kw_alwaysinline:
      case lltok::kw_builtin:
      case lltok::kw_inlinehint:
      case lltok::kw_jumptable:
      case lltok::kw_minsize:
      case lltok::kw_naked:
      case lltok::kw_nobuiltin:
      case lltok::kw_noduplicate:
      case lltok::kw_noimplicitfloat:
      case lltok::kw_noinline:
      case lltok::kw_nonlazybind:
      case lltok::kw_noredzone:
      case lltok::kw_noreturn:
      case lltok::kw_nounwind:
      case lltok::kw_optnone:
      case lltok::kw_optsize:
      case lltok::kw_returns_twice:
      case lltok::kw_sanitize_address:
      case lltok::kw_sanitize_memory:
      case lltok::kw_sanitize_thread:
      case lltok::kw_ssp:
      case lltok::kw_sspreq:
      case lltok::kw_sspstrong:
      case lltok::kw_uwtable:
        HaveError |= Error(Lex.getLoc(), "invalid use of function-only attribute");
        break;
      }
  
      Lex.Lex();
    }
  }
  
  /// ParseOptionalReturnAttrs - Parse a potentially empty list of return attributes.
  bool LLParser::ParseOptionalReturnAttrs(AttrBuilder &B) {
    bool HaveError = false;
  
    B.clear();
  
    while (1) {
      lltok::Kind Token = Lex.getKind();
      switch (Token) {
      default:  // End of attributes.
        return HaveError;
      case lltok::kw_dereferenceable: {
        uint64_t Bytes;
        if (ParseOptionalDereferenceableBytes(Bytes))
          return true;
        B.addDereferenceableAttr(Bytes);
        continue;
      }
      case lltok::kw_inreg:           B.addAttribute(Attribute::InReg); break;
      case lltok::kw_noalias:         B.addAttribute(Attribute::NoAlias); break;
      case lltok::kw_nonnull:         B.addAttribute(Attribute::NonNull); break;
      case lltok::kw_signext:         B.addAttribute(Attribute::SExt); break;
      case lltok::kw_zeroext:         B.addAttribute(Attribute::ZExt); break;
  
      // Error handling.
      case lltok::kw_align:
      case lltok::kw_byval:
      case lltok::kw_inalloca:
      case lltok::kw_nest:
      case lltok::kw_nocapture:
      case lltok::kw_returned:
      case lltok::kw_sret:
        HaveError |= Error(Lex.getLoc(), "invalid use of parameter-only attribute");
        break;
  
      case lltok::kw_alignstack:
      case lltok::kw_alwaysinline:
      case lltok::kw_builtin:
      case lltok::kw_cold:
      case lltok::kw_inlinehint:
      case lltok::kw_jumptable:
      case lltok::kw_minsize:
      case lltok::kw_naked:
      case lltok::kw_nobuiltin:
      case lltok::kw_noduplicate:
      case lltok::kw_noimplicitfloat:
      case lltok::kw_noinline:
      case lltok::kw_nonlazybind:
      case lltok::kw_noredzone:
      case lltok::kw_noreturn:
      case lltok::kw_nounwind:
      case lltok::kw_optnone:
      case lltok::kw_optsize:
      case lltok::kw_returns_twice:
      case lltok::kw_sanitize_address:
      case lltok::kw_sanitize_memory:
      case lltok::kw_sanitize_thread:
      case lltok::kw_ssp:
      case lltok::kw_sspreq:
      case lltok::kw_sspstrong:
      case lltok::kw_uwtable:
        HaveError |= Error(Lex.getLoc(), "invalid use of function-only attribute");
        break;
  
      case lltok::kw_readnone:
      case lltok::kw_readonly:
        HaveError |= Error(Lex.getLoc(), "invalid use of attribute on return type");
      }
  
      Lex.Lex();
    }
  }
  
  /// ParseOptionalLinkage
  ///   ::= /*empty*/
  ///   ::= 'private'
  ///   ::= 'internal'
  ///   ::= 'weak'
  ///   ::= 'weak_odr'
  ///   ::= 'linkonce'
  ///   ::= 'linkonce_odr'
  ///   ::= 'available_externally'
  ///   ::= 'appending'
  ///   ::= 'common'
  ///   ::= 'extern_weak'
  ///   ::= 'external'
  bool LLParser::ParseOptionalLinkage(unsigned &Res, bool &HasLinkage) {
    HasLinkage = false;
    switch (Lex.getKind()) {
    default:                       Res=GlobalValue::ExternalLinkage; return false;
    case lltok::kw_private:        Res = GlobalValue::PrivateLinkage;       break;
    case lltok::kw_internal:       Res = GlobalValue::InternalLinkage;      break;
    case lltok::kw_weak:           Res = GlobalValue::WeakAnyLinkage;       break;
    case lltok::kw_weak_odr:       Res = GlobalValue::WeakODRLinkage;       break;
    case lltok::kw_linkonce:       Res = GlobalValue::LinkOnceAnyLinkage;   break;
    case lltok::kw_linkonce_odr:   Res = GlobalValue::LinkOnceODRLinkage;   break;
    case lltok::kw_available_externally:
      Res = GlobalValue::AvailableExternallyLinkage;
      break;
    case lltok::kw_appending:      Res = GlobalValue::AppendingLinkage;     break;
    case lltok::kw_common:         Res = GlobalValue::CommonLinkage;        break;
    case lltok::kw_extern_weak:    Res = GlobalValue::ExternalWeakLinkage;  break;
    case lltok::kw_external:       Res = GlobalValue::ExternalLinkage;      break;
    }
    Lex.Lex();
    HasLinkage = true;
    return false;
  }
  
  /// ParseOptionalVisibility
  ///   ::= /*empty*/
  ///   ::= 'default'
  ///   ::= 'hidden'
  ///   ::= 'protected'
  ///
  bool LLParser::ParseOptionalVisibility(unsigned &Res) {
    switch (Lex.getKind()) {
    default:                  Res = GlobalValue::DefaultVisibility; return false;
    case lltok::kw_default:   Res = GlobalValue::DefaultVisibility; break;
    case lltok::kw_hidden:    Res = GlobalValue::HiddenVisibility; break;
    case lltok::kw_protected: Res = GlobalValue::ProtectedVisibility; break;
    }
    Lex.Lex();
    return false;
  }
  
  /// ParseOptionalDLLStorageClass
  ///   ::= /*empty*/
  ///   ::= 'dllimport'
  ///   ::= 'dllexport'
  ///
  bool LLParser::ParseOptionalDLLStorageClass(unsigned &Res) {
    switch (Lex.getKind()) {
    default:                  Res = GlobalValue::DefaultStorageClass; return false;
    case lltok::kw_dllimport: Res = GlobalValue::DLLImportStorageClass; break;
    case lltok::kw_dllexport: Res = GlobalValue::DLLExportStorageClass; break;
    }
    Lex.Lex();
    return false;
  }
  
  /// ParseOptionalCallingConv
  ///   ::= /*empty*/
  ///   ::= 'ccc'
  ///   ::= 'fastcc'
  ///   ::= 'intel_ocl_bicc'
  ///   ::= 'coldcc'
  ///   ::= 'x86_stdcallcc'
  ///   ::= 'x86_fastcallcc'
  ///   ::= 'x86_thiscallcc'
  ///   ::= 'x86_vectorcallcc'
  ///   ::= 'arm_apcscc'
  ///   ::= 'arm_aapcscc'
  ///   ::= 'arm_aapcs_vfpcc'
  ///   ::= 'msp430_intrcc'
  ///   ::= 'ptx_kernel'
  ///   ::= 'ptx_device'
  ///   ::= 'spir_func'
  ///   ::= 'spir_kernel'
  ///   ::= 'x86_64_sysvcc'
  ///   ::= 'x86_64_win64cc'
  ///   ::= 'webkit_jscc'
  ///   ::= 'anyregcc'
  ///   ::= 'preserve_mostcc'
  ///   ::= 'preserve_allcc'
  ///   ::= 'ghccc'
  ///   ::= 'cc' UINT
  ///
  bool LLParser::ParseOptionalCallingConv(unsigned &CC) {
    switch (Lex.getKind()) {
    default:                       CC = CallingConv::C; return false;
    case lltok::kw_ccc:            CC = CallingConv::C; break;
    case lltok::kw_fastcc:         CC = CallingConv::Fast; break;
    case lltok::kw_coldcc:         CC = CallingConv::Cold; break;
    case lltok::kw_x86_stdcallcc:  CC = CallingConv::X86_StdCall; break;
    case lltok::kw_x86_fastcallcc: CC = CallingConv::X86_FastCall; break;
    case lltok::kw_x86_thiscallcc: CC = CallingConv::X86_ThisCall; break;
    case lltok::kw_x86_vectorcallcc:CC = CallingConv::X86_VectorCall; break;
    case lltok::kw_arm_apcscc:     CC = CallingConv::ARM_APCS; break;
    case lltok::kw_arm_aapcscc:    CC = CallingConv::ARM_AAPCS; break;
    case lltok::kw_arm_aapcs_vfpcc:CC = CallingConv::ARM_AAPCS_VFP; break;
    case lltok::kw_msp430_intrcc:  CC = CallingConv::MSP430_INTR; break;
    case lltok::kw_ptx_kernel:     CC = CallingConv::PTX_Kernel; break;
    case lltok::kw_ptx_device:     CC = CallingConv::PTX_Device; break;
    case lltok::kw_spir_kernel:    CC = CallingConv::SPIR_KERNEL; break;
    case lltok::kw_spir_func:      CC = CallingConv::SPIR_FUNC; break;
    case lltok::kw_intel_ocl_bicc: CC = CallingConv::Intel_OCL_BI; break;
    case lltok::kw_x86_64_sysvcc:  CC = CallingConv::X86_64_SysV; break;
    case lltok::kw_x86_64_win64cc: CC = CallingConv::X86_64_Win64; break;
    case lltok::kw_webkit_jscc:    CC = CallingConv::WebKit_JS; break;
    case lltok::kw_anyregcc:       CC = CallingConv::AnyReg; break;
    case lltok::kw_preserve_mostcc:CC = CallingConv::PreserveMost; break;
    case lltok::kw_preserve_allcc: CC = CallingConv::PreserveAll; break;
    case lltok::kw_ghccc:          CC = CallingConv::GHC; break;
    case lltok::kw_cc: {
        Lex.Lex();
        return ParseUInt32(CC);
      }
    }
  
    Lex.Lex();
    return false;
  }
  
  /// ParseInstructionMetadata
  ///   ::= !dbg !42 (',' !dbg !57)*
  bool LLParser::ParseInstructionMetadata(Instruction *Inst,
                                          PerFunctionState *PFS) {
    do {
      if (Lex.getKind() != lltok::MetadataVar)
        return TokError("expected metadata after comma");
  
      std::string Name = Lex.getStrVal();
      unsigned MDK = M->getMDKindID(Name);
      Lex.Lex();
  
      MDNode *N;
      if (ParseMDNode(N))
        return true;
  
      Inst->setMetadata(MDK, N);
      if (MDK == LLVMContext::MD_tbaa)
        InstsWithTBAATag.push_back(Inst);
  
      // If this is the end of the list, we're done.
    } while (EatIfPresent(lltok::comma));
    return false;
  }
  
  /// ParseOptionalAlignment
  ///   ::= /* empty */
  ///   ::= 'align' 4
  bool LLParser::ParseOptionalAlignment(unsigned &Alignment) {
    Alignment = 0;
    if (!EatIfPresent(lltok::kw_align))
      return false;
    LocTy AlignLoc = Lex.getLoc();
    if (ParseUInt32(Alignment)) return true;
    if (!isPowerOf2_32(Alignment))
      return Error(AlignLoc, "alignment is not a power of two");
    if (Alignment > Value::MaximumAlignment)
      return Error(AlignLoc, "huge alignments are not supported yet");
    return false;
  }
  
  /// ParseOptionalDereferenceableBytes
  ///   ::= /* empty */
  ///   ::= 'dereferenceable' '(' 4 ')'
  bool LLParser::ParseOptionalDereferenceableBytes(uint64_t &Bytes) {
    Bytes = 0;
    if (!EatIfPresent(lltok::kw_dereferenceable))
      return false;
    LocTy ParenLoc = Lex.getLoc();
    if (!EatIfPresent(lltok::lparen))
      return Error(ParenLoc, "expected '('");
    LocTy DerefLoc = Lex.getLoc();
    if (ParseUInt64(Bytes)) return true;
    ParenLoc = Lex.getLoc();
    if (!EatIfPresent(lltok::rparen))
      return Error(ParenLoc, "expected ')'");
    if (!Bytes)
      return Error(DerefLoc, "dereferenceable bytes must be non-zero");
    return false;
  }
  
  /// ParseOptionalCommaAlign
  ///   ::=
  ///   ::= ',' align 4
  ///
  /// This returns with AteExtraComma set to true if it ate an excess comma at the
  /// end.
  bool LLParser::ParseOptionalCommaAlign(unsigned &Alignment,
                                         bool &AteExtraComma) {
    AteExtraComma = false;
    while (EatIfPresent(lltok::comma)) {
      // Metadata at the end is an early exit.
      if (Lex.getKind() == lltok::MetadataVar) {
        AteExtraComma = true;
        return false;
      }
  
      if (Lex.getKind() != lltok::kw_align)
        return Error(Lex.getLoc(), "expected metadata or 'align'");
  
      if (ParseOptionalAlignment(Alignment)) return true;
    }
  
    return false;
  }
  
  /// ParseScopeAndOrdering
  ///   if isAtomic: ::= 'singlethread'? AtomicOrdering
  ///   else: ::=
  ///
  /// This sets Scope and Ordering to the parsed values.
  bool LLParser::ParseScopeAndOrdering(bool isAtomic, SynchronizationScope &Scope,
                                       AtomicOrdering &Ordering) {
    if (!isAtomic)
      return false;
  
    Scope = CrossThread;
    if (EatIfPresent(lltok::kw_singlethread))
      Scope = SingleThread;
  
    return ParseOrdering(Ordering);
  }
  
  /// ParseOrdering
  ///   ::= AtomicOrdering
  ///
  /// This sets Ordering to the parsed value.
  bool LLParser::ParseOrdering(AtomicOrdering &Ordering) {
    switch (Lex.getKind()) {
    default: return TokError("Expected ordering on atomic instruction");
    case lltok::kw_unordered: Ordering = Unordered; break;
    case lltok::kw_monotonic: Ordering = Monotonic; break;
    case lltok::kw_acquire: Ordering = Acquire; break;
    case lltok::kw_release: Ordering = Release; break;
    case lltok::kw_acq_rel: Ordering = AcquireRelease; break;
    case lltok::kw_seq_cst: Ordering = SequentiallyConsistent; break;
    }
    Lex.Lex();
    return false;
  }
  
  /// ParseOptionalStackAlignment
  ///   ::= /* empty */
  ///   ::= 'alignstack' '(' 4 ')'
  bool LLParser::ParseOptionalStackAlignment(unsigned &Alignment) {
    Alignment = 0;
    if (!EatIfPresent(lltok::kw_alignstack))
      return false;
    LocTy ParenLoc = Lex.getLoc();
    if (!EatIfPresent(lltok::lparen))
      return Error(ParenLoc, "expected '('");
    LocTy AlignLoc = Lex.getLoc();
    if (ParseUInt32(Alignment)) return true;
    ParenLoc = Lex.getLoc();
    if (!EatIfPresent(lltok::rparen))
      return Error(ParenLoc, "expected ')'");
    if (!isPowerOf2_32(Alignment))
      return Error(AlignLoc, "stack alignment is not a power of two");
    return false;
  }
  
  /// ParseIndexList - This parses the index list for an insert/extractvalue
  /// instruction.  This sets AteExtraComma in the case where we eat an extra
  /// comma at the end of the line and find that it is followed by metadata.
  /// Clients that don't allow metadata can call the version of this function that
  /// only takes one argument.
  ///
  /// ParseIndexList
  ///    ::=  (',' uint32)+
  ///
  bool LLParser::ParseIndexList(SmallVectorImpl<unsigned> &Indices,
                                bool &AteExtraComma) {
    AteExtraComma = false;
  
    if (Lex.getKind() != lltok::comma)
      return TokError("expected ',' as start of index list");
  
    while (EatIfPresent(lltok::comma)) {
      if (Lex.getKind() == lltok::MetadataVar) {
        AteExtraComma = true;
        return false;
      }
      unsigned Idx = 0;
      if (ParseUInt32(Idx)) return true;
      Indices.push_back(Idx);
    }
  
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Type Parsing.
  //===----------------------------------------------------------------------===//
  
  /// ParseType - Parse a type.
  bool LLParser::ParseType(Type *&Result, const Twine &Msg, bool AllowVoid) {
    SMLoc TypeLoc = Lex.getLoc();
    switch (Lex.getKind()) {
    default:
      return TokError(Msg);
    case lltok::Type:
      // Type ::= 'float' | 'void' (etc)
      Result = Lex.getTyVal();
      Lex.Lex();
      break;
    case lltok::lbrace:
      // Type ::= StructType
      if (ParseAnonStructType(Result, false))
        return true;
      break;
    case lltok::lsquare:
      // Type ::= '[' ... ']'
      Lex.Lex(); // eat the lsquare.
      if (ParseArrayVectorType(Result, false))
        return true;
      break;
    case lltok::less: // Either vector or packed struct.
      // Type ::= '<' ... '>'
      Lex.Lex();
      if (Lex.getKind() == lltok::lbrace) {
        if (ParseAnonStructType(Result, true) ||
            ParseToken(lltok::greater, "expected '>' at end of packed struct"))
          return true;
      } else if (ParseArrayVectorType(Result, true))
        return true;
      break;
    case lltok::LocalVar: {
      // Type ::= %foo
      std::pair<Type*, LocTy> &Entry = NamedTypes[Lex.getStrVal()];
  
      // If the type hasn't been defined yet, create a forward definition and
      // remember where that forward def'n was seen (in case it never is defined).
      if (!Entry.first) {
        Entry.first = StructType::create(Context, Lex.getStrVal());
        Entry.second = Lex.getLoc();
      }
      Result = Entry.first;
      Lex.Lex();
      break;
    }
  
    case lltok::LocalVarID: {
      // Type ::= %4
      if (Lex.getUIntVal() >= NumberedTypes.size())
        NumberedTypes.resize(Lex.getUIntVal()+1);
      std::pair<Type*, LocTy> &Entry = NumberedTypes[Lex.getUIntVal()];
  
      // If the type hasn't been defined yet, create a forward definition and
      // remember where that forward def'n was seen (in case it never is defined).
      if (!Entry.first) {
        Entry.first = StructType::create(Context);
        Entry.second = Lex.getLoc();
      }
      Result = Entry.first;
      Lex.Lex();
      break;
    }
    }
  
    // Parse the type suffixes.
    while (1) {
      switch (Lex.getKind()) {
      // End of type.
      default:
        if (!AllowVoid && Result->isVoidTy())
          return Error(TypeLoc, "void type only allowed for function results");
        return false;
  
      // Type ::= Type '*'
      case lltok::star:
        if (Result->isLabelTy())
          return TokError("basic block pointers are invalid");
        if (Result->isVoidTy())
          return TokError("pointers to void are invalid - use i8* instead");
        if (!PointerType::isValidElementType(Result))
          return TokError("pointer to this type is invalid");
        Result = PointerType::getUnqual(Result);
        Lex.Lex();
        break;
  
      // Type ::= Type 'addrspace' '(' uint32 ')' '*'
      case lltok::kw_addrspace: {
        if (Result->isLabelTy())
          return TokError("basic block pointers are invalid");
        if (Result->isVoidTy())
          return TokError("pointers to void are invalid; use i8* instead");
        if (!PointerType::isValidElementType(Result))
          return TokError("pointer to this type is invalid");
        unsigned AddrSpace;
        if (ParseOptionalAddrSpace(AddrSpace) ||
            ParseToken(lltok::star, "expected '*' in address space"))
          return true;
  
        Result = PointerType::get(Result, AddrSpace);
        break;
      }
  
      /// Types '(' ArgTypeListI ')' OptFuncAttrs
      case lltok::lparen:
        if (ParseFunctionType(Result))
          return true;
        break;
      }
    }
  }
  
  /// ParseParameterList
  ///    ::= '(' ')'
  ///    ::= '(' Arg (',' Arg)* ')'
  ///  Arg
  ///    ::= Type OptionalAttributes Value OptionalAttributes
  bool LLParser::ParseParameterList(SmallVectorImpl<ParamInfo> &ArgList,
                                    PerFunctionState &PFS, bool IsMustTailCall,
                                    bool InVarArgsFunc) {
    if (ParseToken(lltok::lparen, "expected '(' in call"))
      return true;
  
    unsigned AttrIndex = 1;
    while (Lex.getKind() != lltok::rparen) {
      // If this isn't the first argument, we need a comma.
      if (!ArgList.empty() &&
          ParseToken(lltok::comma, "expected ',' in argument list"))
        return true;
  
      // Parse an ellipsis if this is a musttail call in a variadic function.
      if (Lex.getKind() == lltok::dotdotdot) {
        const char *Msg = "unexpected ellipsis in argument list for ";
        if (!IsMustTailCall)
          return TokError(Twine(Msg) + "non-musttail call");
        if (!InVarArgsFunc)
          return TokError(Twine(Msg) + "musttail call in non-varargs function");
        Lex.Lex();  // Lex the '...', it is purely for readability.
        return ParseToken(lltok::rparen, "expected ')' at end of argument list");
      }
  
      // Parse the argument.
      LocTy ArgLoc;
      Type *ArgTy = nullptr;
      AttrBuilder ArgAttrs;
      Value *V;
      if (ParseType(ArgTy, ArgLoc))
        return true;
  
      if (ArgTy->isMetadataTy()) {
        if (ParseMetadataAsValue(V, PFS))
          return true;
      } else {
        // Otherwise, handle normal operands.
        if (ParseOptionalParamAttrs(ArgAttrs) || ParseValue(ArgTy, V, PFS))
          return true;
      }
      ArgList.push_back(ParamInfo(ArgLoc, V, AttributeSet::get(V->getContext(),
                                                               AttrIndex++,
                                                               ArgAttrs)));
    }
  
    if (IsMustTailCall && InVarArgsFunc)
      return TokError("expected '...' at end of argument list for musttail call "
                      "in varargs function");
  
    Lex.Lex();  // Lex the ')'.
    return false;
  }
  
  
  
  /// ParseArgumentList - Parse the argument list for a function type or function
  /// prototype.
  ///   ::= '(' ArgTypeListI ')'
  /// ArgTypeListI
  ///   ::= /*empty*/
  ///   ::= '...'
  ///   ::= ArgTypeList ',' '...'
  ///   ::= ArgType (',' ArgType)*
  ///
  bool LLParser::ParseArgumentList(SmallVectorImpl<ArgInfo> &ArgList,
                                   bool &isVarArg){
    isVarArg = false;
    assert(Lex.getKind() == lltok::lparen);
    Lex.Lex(); // eat the (.
  
    if (Lex.getKind() == lltok::rparen) {
      // empty
    } else if (Lex.getKind() == lltok::dotdotdot) {
      isVarArg = true;
      Lex.Lex();
    } else {
      LocTy TypeLoc = Lex.getLoc();
      Type *ArgTy = nullptr;
      AttrBuilder Attrs;
      std::string Name;
  
      if (ParseType(ArgTy) ||
          ParseOptionalParamAttrs(Attrs)) return true;
  
      if (ArgTy->isVoidTy())
        return Error(TypeLoc, "argument can not have void type");
  
      if (Lex.getKind() == lltok::LocalVar) {
        Name = Lex.getStrVal();
        Lex.Lex();
      }
  
      if (!FunctionType::isValidArgumentType(ArgTy))
        return Error(TypeLoc, "invalid type for function argument");
  
      unsigned AttrIndex = 1;
      ArgList.push_back(ArgInfo(TypeLoc, ArgTy,
                                AttributeSet::get(ArgTy->getContext(),
                                                  AttrIndex++, Attrs), Name));
  
      while (EatIfPresent(lltok::comma)) {
        // Handle ... at end of arg list.
        if (EatIfPresent(lltok::dotdotdot)) {
          isVarArg = true;
          break;
        }
  
        // Otherwise must be an argument type.
        TypeLoc = Lex.getLoc();
        if (ParseType(ArgTy) || ParseOptionalParamAttrs(Attrs)) return true;
  
        if (ArgTy->isVoidTy())
          return Error(TypeLoc, "argument can not have void type");
  
        if (Lex.getKind() == lltok::LocalVar) {
          Name = Lex.getStrVal();
          Lex.Lex();
        } else {
          Name = "";
        }
  
        if (!ArgTy->isFirstClassType())
          return Error(TypeLoc, "invalid type for function argument");
  
        ArgList.push_back(ArgInfo(TypeLoc, ArgTy,
                                  AttributeSet::get(ArgTy->getContext(),
                                                    AttrIndex++, Attrs),
                                  Name));
      }
    }
  
    return ParseToken(lltok::rparen, "expected ')' at end of argument list");
  }
  
  /// ParseFunctionType
  ///  ::= Type ArgumentList OptionalAttrs
  bool LLParser::ParseFunctionType(Type *&Result) {
    assert(Lex.getKind() == lltok::lparen);
  
    if (!FunctionType::isValidReturnType(Result))
      return TokError("invalid function return type");
  
    SmallVector<ArgInfo, 8> ArgList;
    bool isVarArg;
    if (ParseArgumentList(ArgList, isVarArg))
      return true;
  
    // Reject names on the arguments lists.
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i) {
      if (!ArgList[i].Name.empty())
        return Error(ArgList[i].Loc, "argument name invalid in function type");
      if (ArgList[i].Attrs.hasAttributes(i + 1))
        return Error(ArgList[i].Loc,
                     "argument attributes invalid in function type");
    }
  
    SmallVector<Type*, 16> ArgListTy;
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i)
      ArgListTy.push_back(ArgList[i].Ty);
  
    Result = FunctionType::get(Result, ArgListTy, isVarArg);
    return false;
  }
  
  /// ParseAnonStructType - Parse an anonymous struct type, which is inlined into
  /// other structs.
  bool LLParser::ParseAnonStructType(Type *&Result, bool Packed) {
    SmallVector<Type*, 8> Elts;
    if (ParseStructBody(Elts)) return true;
  
    Result = StructType::get(Context, Elts, Packed);
    return false;
  }
  
  /// ParseStructDefinition - Parse a struct in a 'type' definition.
  bool LLParser::ParseStructDefinition(SMLoc TypeLoc, StringRef Name,
                                       std::pair<Type*, LocTy> &Entry,
                                       Type *&ResultTy) {
    // If the type was already defined, diagnose the redefinition.
    if (Entry.first && !Entry.second.isValid())
      return Error(TypeLoc, "redefinition of type");
  
    // If we have opaque, just return without filling in the definition for the
    // struct.  This counts as a definition as far as the .ll file goes.
    if (EatIfPresent(lltok::kw_opaque)) {
      // This type is being defined, so clear the location to indicate this.
      Entry.second = SMLoc();
  
      // If this type number has never been uttered, create it.
      if (!Entry.first)
        Entry.first = StructType::create(Context, Name);
      ResultTy = Entry.first;
      return false;
    }
  
    // If the type starts with '<', then it is either a packed struct or a vector.
    bool isPacked = EatIfPresent(lltok::less);
  
    // If we don't have a struct, then we have a random type alias, which we
    // accept for compatibility with old files.  These types are not allowed to be
    // forward referenced and not allowed to be recursive.
    if (Lex.getKind() != lltok::lbrace) {
      if (Entry.first)
        return Error(TypeLoc, "forward references to non-struct type");
  
      ResultTy = nullptr;
      if (isPacked)
        return ParseArrayVectorType(ResultTy, true);
      return ParseType(ResultTy);
    }
  
    // This type is being defined, so clear the location to indicate this.
    Entry.second = SMLoc();
  
    // If this type number has never been uttered, create it.
    if (!Entry.first)
      Entry.first = StructType::create(Context, Name);
  
    StructType *STy = cast<StructType>(Entry.first);
  
    SmallVector<Type*, 8> Body;
    if (ParseStructBody(Body) ||
        (isPacked && ParseToken(lltok::greater, "expected '>' in packed struct")))
      return true;
  
    STy->setBody(Body, isPacked);
    ResultTy = STy;
    return false;
  }
  
  
  /// ParseStructType: Handles packed and unpacked types.  </> parsed elsewhere.
  ///   StructType
  ///     ::= '{' '}'
  ///     ::= '{' Type (',' Type)* '}'
  ///     ::= '<' '{' '}' '>'
  ///     ::= '<' '{' Type (',' Type)* '}' '>'
  bool LLParser::ParseStructBody(SmallVectorImpl<Type*> &Body) {
    assert(Lex.getKind() == lltok::lbrace);
    Lex.Lex(); // Consume the '{'
  
    // Handle the empty struct.
    if (EatIfPresent(lltok::rbrace))
      return false;
  
    LocTy EltTyLoc = Lex.getLoc();
    Type *Ty = nullptr;
    if (ParseType(Ty)) return true;
    Body.push_back(Ty);
  
    if (!StructType::isValidElementType(Ty))
      return Error(EltTyLoc, "invalid element type for struct");
  
    while (EatIfPresent(lltok::comma)) {
      EltTyLoc = Lex.getLoc();
      if (ParseType(Ty)) return true;
  
      if (!StructType::isValidElementType(Ty))
        return Error(EltTyLoc, "invalid element type for struct");
  
      Body.push_back(Ty);
    }
  
    return ParseToken(lltok::rbrace, "expected '}' at end of struct");
  }
  
  /// ParseArrayVectorType - Parse an array or vector type, assuming the first
  /// token has already been consumed.
  ///   Type
  ///     ::= '[' APSINTVAL 'x' Types ']'
  ///     ::= '<' APSINTVAL 'x' Types '>'
  bool LLParser::ParseArrayVectorType(Type *&Result, bool isVector) {
    if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned() ||
        Lex.getAPSIntVal().getBitWidth() > 64)
      return TokError("expected number in address space");
  
    LocTy SizeLoc = Lex.getLoc();
    uint64_t Size = Lex.getAPSIntVal().getZExtValue();
    Lex.Lex();
  
    if (ParseToken(lltok::kw_x, "expected 'x' after element count"))
        return true;
  
    LocTy TypeLoc = Lex.getLoc();
    Type *EltTy = nullptr;
    if (ParseType(EltTy)) return true;
  
    if (ParseToken(isVector ? lltok::greater : lltok::rsquare,
                   "expected end of sequential type"))
      return true;
  
    if (isVector) {
      if (Size == 0)
        return Error(SizeLoc, "zero element vector is illegal");
      if ((unsigned)Size != Size)
        return Error(SizeLoc, "size too large for vector");
      if (!VectorType::isValidElementType(EltTy))
        return Error(TypeLoc, "invalid vector element type");
      Result = VectorType::get(EltTy, unsigned(Size));
    } else {
      if (!ArrayType::isValidElementType(EltTy))
        return Error(TypeLoc, "invalid array element type");
      Result = ArrayType::get(EltTy, Size);
    }
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Function Semantic Analysis.
  //===----------------------------------------------------------------------===//
  
  LLParser::PerFunctionState::PerFunctionState(LLParser &p, Function &f,
                                               int functionNumber)
    : P(p), F(f), FunctionNumber(functionNumber) {
  
    // Insert unnamed arguments into the NumberedVals list.
    for (Function::arg_iterator AI = F.arg_begin(), E = F.arg_end();
         AI != E; ++AI)
      if (!AI->hasName())
        NumberedVals.push_back(AI);
  }
  
  LLParser::PerFunctionState::~PerFunctionState() {
    // If there were any forward referenced non-basicblock values, delete them.
    for (std::map<std::string, std::pair<Value*, LocTy> >::iterator
         I = ForwardRefVals.begin(), E = ForwardRefVals.end(); I != E; ++I)
      if (!isa<BasicBlock>(I->second.first)) {
        I->second.first->replaceAllUsesWith(
                             UndefValue::get(I->second.first->getType()));
        delete I->second.first;
        I->second.first = nullptr;
      }
  
    for (std::map<unsigned, std::pair<Value*, LocTy> >::iterator
         I = ForwardRefValIDs.begin(), E = ForwardRefValIDs.end(); I != E; ++I)
      if (!isa<BasicBlock>(I->second.first)) {
        I->second.first->replaceAllUsesWith(
                             UndefValue::get(I->second.first->getType()));
        delete I->second.first;
        I->second.first = nullptr;
      }
  }
  
  bool LLParser::PerFunctionState::FinishFunction() {
    if (!ForwardRefVals.empty())
      return P.Error(ForwardRefVals.begin()->second.second,
                     "use of undefined value '%" + ForwardRefVals.begin()->first +
                     "'");
    if (!ForwardRefValIDs.empty())
      return P.Error(ForwardRefValIDs.begin()->second.second,
                     "use of undefined value '%" +
                     Twine(ForwardRefValIDs.begin()->first) + "'");
    return false;
  }
  
  
  /// GetVal - Get a value with the specified name or ID, creating a
  /// forward reference record if needed.  This can return null if the value
  /// exists but does not have the right type.
  Value *LLParser::PerFunctionState::GetVal(const std::string &Name,
                                            Type *Ty, LocTy Loc) {
    // Look this name up in the normal function symbol table.
    Value *Val = F.getValueSymbolTable().lookup(Name);
  
    // If this is a forward reference for the value, see if we already created a
    // forward ref record.
    if (!Val) {
      std::map<std::string, std::pair<Value*, LocTy> >::iterator
        I = ForwardRefVals.find(Name);
      if (I != ForwardRefVals.end())
        Val = I->second.first;
    }
  
    // If we have the value in the symbol table or fwd-ref table, return it.
    if (Val) {
      if (Val->getType() == Ty) return Val;
      if (Ty->isLabelTy())
        P.Error(Loc, "'%" + Name + "' is not a basic block");
      else
        P.Error(Loc, "'%" + Name + "' defined with type '" +
                getTypeString(Val->getType()) + "'");
      return nullptr;
    }
  
    // Don't make placeholders with invalid type.
    if (!Ty->isFirstClassType()) {
      P.Error(Loc, "invalid use of a non-first-class type");
      return nullptr;
    }
  
    // Otherwise, create a new forward reference for this value and remember it.
    Value *FwdVal;
    if (Ty->isLabelTy())
      FwdVal = BasicBlock::Create(F.getContext(), Name, &F);
    else
      FwdVal = new Argument(Ty, Name);
  
    ForwardRefVals[Name] = std::make_pair(FwdVal, Loc);
    return FwdVal;
  }
  
  Value *LLParser::PerFunctionState::GetVal(unsigned ID, Type *Ty,
                                            LocTy Loc) {
    // Look this name up in the normal function symbol table.
    Value *Val = ID < NumberedVals.size() ? NumberedVals[ID] : nullptr;
  
    // If this is a forward reference for the value, see if we already created a
    // forward ref record.
    if (!Val) {
      std::map<unsigned, std::pair<Value*, LocTy> >::iterator
        I = ForwardRefValIDs.find(ID);
      if (I != ForwardRefValIDs.end())
        Val = I->second.first;
    }
  
    // If we have the value in the symbol table or fwd-ref table, return it.
    if (Val) {
      if (Val->getType() == Ty) return Val;
      if (Ty->isLabelTy())
        P.Error(Loc, "'%" + Twine(ID) + "' is not a basic block");
      else
        P.Error(Loc, "'%" + Twine(ID) + "' defined with type '" +
                getTypeString(Val->getType()) + "'");
      return nullptr;
    }
  
    if (!Ty->isFirstClassType()) {
      P.Error(Loc, "invalid use of a non-first-class type");
      return nullptr;
    }
  
    // Otherwise, create a new forward reference for this value and remember it.
    Value *FwdVal;
    if (Ty->isLabelTy())
      FwdVal = BasicBlock::Create(F.getContext(), "", &F);
    else
      FwdVal = new Argument(Ty);
  
    ForwardRefValIDs[ID] = std::make_pair(FwdVal, Loc);
    return FwdVal;
  }
  
  /// SetInstName - After an instruction is parsed and inserted into its
  /// basic block, this installs its name.
  bool LLParser::PerFunctionState::SetInstName(int NameID,
                                               const std::string &NameStr,
                                               LocTy NameLoc, Instruction *Inst) {
    // If this instruction has void type, it cannot have a name or ID specified.
    if (Inst->getType()->isVoidTy()) {
      if (NameID != -1 || !NameStr.empty())
        return P.Error(NameLoc, "instructions returning void cannot have a name");
      return false;
    }
  
    // If this was a numbered instruction, verify that the instruction is the
    // expected value and resolve any forward references.
    if (NameStr.empty()) {
      // If neither a name nor an ID was specified, just use the next ID.
      if (NameID == -1)
        NameID = NumberedVals.size();
  
      if (unsigned(NameID) != NumberedVals.size())
        return P.Error(NameLoc, "instruction expected to be numbered '%" +
                       Twine(NumberedVals.size()) + "'");
  
      std::map<unsigned, std::pair<Value*, LocTy> >::iterator FI =
        ForwardRefValIDs.find(NameID);
      if (FI != ForwardRefValIDs.end()) {
        if (FI->second.first->getType() != Inst->getType())
          return P.Error(NameLoc, "instruction forward referenced with type '" +
                         getTypeString(FI->second.first->getType()) + "'");
        FI->second.first->replaceAllUsesWith(Inst);
        delete FI->second.first;
        ForwardRefValIDs.erase(FI);
      }
  
      NumberedVals.push_back(Inst);
      return false;
    }
  
    // Otherwise, the instruction had a name.  Resolve forward refs and set it.
    std::map<std::string, std::pair<Value*, LocTy> >::iterator
      FI = ForwardRefVals.find(NameStr);
    if (FI != ForwardRefVals.end()) {
      if (FI->second.first->getType() != Inst->getType())
        return P.Error(NameLoc, "instruction forward referenced with type '" +
                       getTypeString(FI->second.first->getType()) + "'");
      FI->second.first->replaceAllUsesWith(Inst);
      delete FI->second.first;
      ForwardRefVals.erase(FI);
    }
  
    // Set the name on the instruction.
    Inst->setName(NameStr);
  
    if (Inst->getName() != NameStr)
      return P.Error(NameLoc, "multiple definition of local value named '" +
                     NameStr + "'");
    return false;
  }
  
  /// GetBB - Get a basic block with the specified name or ID, creating a
  /// forward reference record if needed.
  BasicBlock *LLParser::PerFunctionState::GetBB(const std::string &Name,
                                                LocTy Loc) {
    return cast_or_null<BasicBlock>(GetVal(Name,
                                          Type::getLabelTy(F.getContext()), Loc));
  }
  
  BasicBlock *LLParser::PerFunctionState::GetBB(unsigned ID, LocTy Loc) {
    return cast_or_null<BasicBlock>(GetVal(ID,
                                          Type::getLabelTy(F.getContext()), Loc));
  }
  
  /// DefineBB - Define the specified basic block, which is either named or
  /// unnamed.  If there is an error, this returns null otherwise it returns
  /// the block being defined.
  BasicBlock *LLParser::PerFunctionState::DefineBB(const std::string &Name,
                                                   LocTy Loc) {
    BasicBlock *BB;
    if (Name.empty())
      BB = GetBB(NumberedVals.size(), Loc);
    else
      BB = GetBB(Name, Loc);
    if (!BB) return nullptr; // Already diagnosed error.
  
    // Move the block to the end of the function.  Forward ref'd blocks are
    // inserted wherever they happen to be referenced.
    F.getBasicBlockList().splice(F.end(), F.getBasicBlockList(), BB);
  
    // Remove the block from forward ref sets.
    if (Name.empty()) {
      ForwardRefValIDs.erase(NumberedVals.size());
      NumberedVals.push_back(BB);
    } else {
      // BB forward references are already in the function symbol table.
      ForwardRefVals.erase(Name);
    }
  
    return BB;
  }
  
  //===----------------------------------------------------------------------===//
  // Constants.
  //===----------------------------------------------------------------------===//
  
  /// ParseValID - Parse an abstract value that doesn't necessarily have a
  /// type implied.  For example, if we parse "4" we don't know what integer type
  /// it has.  The value will later be combined with its type and checked for
  /// sanity.  PFS is used to convert function-local operands of metadata (since
  /// metadata operands are not just parsed here but also converted to values).
  /// PFS can be null when we are not parsing metadata values inside a function.
  bool LLParser::ParseValID(ValID &ID, PerFunctionState *PFS) {
    ID.Loc = Lex.getLoc();
    switch (Lex.getKind()) {
    default: return TokError("expected value token");
    case lltok::GlobalID:  // @42
      ID.UIntVal = Lex.getUIntVal();
      ID.Kind = ValID::t_GlobalID;
      break;
    case lltok::GlobalVar:  // @foo
      ID.StrVal = Lex.getStrVal();
      ID.Kind = ValID::t_GlobalName;
      break;
    case lltok::LocalVarID:  // %42
      ID.UIntVal = Lex.getUIntVal();
      ID.Kind = ValID::t_LocalID;
      break;
    case lltok::LocalVar:  // %foo
      ID.StrVal = Lex.getStrVal();
      ID.Kind = ValID::t_LocalName;
      break;
    case lltok::APSInt:
      ID.APSIntVal = Lex.getAPSIntVal();
      ID.Kind = ValID::t_APSInt;
      break;
    case lltok::APFloat:
      ID.APFloatVal = Lex.getAPFloatVal();
      ID.Kind = ValID::t_APFloat;
      break;
    case lltok::kw_true:
      ID.ConstantVal = ConstantInt::getTrue(Context);
      ID.Kind = ValID::t_Constant;
      break;
    case lltok::kw_false:
      ID.ConstantVal = ConstantInt::getFalse(Context);
      ID.Kind = ValID::t_Constant;
      break;
    case lltok::kw_null: ID.Kind = ValID::t_Null; break;
    case lltok::kw_undef: ID.Kind = ValID::t_Undef; break;
    case lltok::kw_zeroinitializer: ID.Kind = ValID::t_Zero; break;
  
    case lltok::lbrace: {
      // ValID ::= '{' ConstVector '}'
      Lex.Lex();
      SmallVector<Constant*, 16> Elts;
      if (ParseGlobalValueVector(Elts) ||
          ParseToken(lltok::rbrace, "expected end of struct constant"))
        return true;
  
      ID.ConstantStructElts = new Constant*[Elts.size()];
      ID.UIntVal = Elts.size();
      memcpy(ID.ConstantStructElts, Elts.data(), Elts.size()*sizeof(Elts[0]));
      ID.Kind = ValID::t_ConstantStruct;
      return false;
    }
    case lltok::less: {
      // ValID ::= '<' ConstVector '>'         --> Vector.
      // ValID ::= '<' '{' ConstVector '}' '>' --> Packed Struct.
      Lex.Lex();
      bool isPackedStruct = EatIfPresent(lltok::lbrace);
  
      SmallVector<Constant*, 16> Elts;
      LocTy FirstEltLoc = Lex.getLoc();
      if (ParseGlobalValueVector(Elts) ||
          (isPackedStruct &&
           ParseToken(lltok::rbrace, "expected end of packed struct")) ||
          ParseToken(lltok::greater, "expected end of constant"))
        return true;
  
      if (isPackedStruct) {
        ID.ConstantStructElts = new Constant*[Elts.size()];
        memcpy(ID.ConstantStructElts, Elts.data(), Elts.size()*sizeof(Elts[0]));
        ID.UIntVal = Elts.size();
        ID.Kind = ValID::t_PackedConstantStruct;
        return false;
      }
  
      if (Elts.empty())
        return Error(ID.Loc, "constant vector must not be empty");
  
      if (!Elts[0]->getType()->isIntegerTy() &&
          !Elts[0]->getType()->isFloatingPointTy() &&
          !Elts[0]->getType()->isPointerTy())
        return Error(FirstEltLoc,
              "vector elements must have integer, pointer or floating point type");
  
      // Verify that all the vector elements have the same type.
      for (unsigned i = 1, e = Elts.size(); i != e; ++i)
        if (Elts[i]->getType() != Elts[0]->getType())
          return Error(FirstEltLoc,
                       "vector element #" + Twine(i) +
                      " is not of type '" + getTypeString(Elts[0]->getType()));
  
      ID.ConstantVal = ConstantVector::get(Elts);
      ID.Kind = ValID::t_Constant;
      return false;
    }
    case lltok::lsquare: {   // Array Constant
      Lex.Lex();
      SmallVector<Constant*, 16> Elts;
      LocTy FirstEltLoc = Lex.getLoc();
      if (ParseGlobalValueVector(Elts) ||
          ParseToken(lltok::rsquare, "expected end of array constant"))
        return true;
  
      // Handle empty element.
      if (Elts.empty()) {
        // Use undef instead of an array because it's inconvenient to determine
        // the element type at this point, there being no elements to examine.
        ID.Kind = ValID::t_EmptyArray;
        return false;
      }
  
      if (!Elts[0]->getType()->isFirstClassType())
        return Error(FirstEltLoc, "invalid array element type: " +
                     getTypeString(Elts[0]->getType()));
  
      ArrayType *ATy = ArrayType::get(Elts[0]->getType(), Elts.size());
  
      // Verify all elements are correct type!
      for (unsigned i = 0, e = Elts.size(); i != e; ++i) {
        if (Elts[i]->getType() != Elts[0]->getType())
          return Error(FirstEltLoc,
                       "array element #" + Twine(i) +
                       " is not of type '" + getTypeString(Elts[0]->getType()));
      }
  
      ID.ConstantVal = ConstantArray::get(ATy, Elts);
      ID.Kind = ValID::t_Constant;
      return false;
    }
    case lltok::kw_c:  // c "foo"
      Lex.Lex();
      ID.ConstantVal = ConstantDataArray::getString(Context, Lex.getStrVal(),
                                                    false);
      if (ParseToken(lltok::StringConstant, "expected string")) return true;
      ID.Kind = ValID::t_Constant;
      return false;
  
    case lltok::kw_asm: {
      // ValID ::= 'asm' SideEffect? AlignStack? IntelDialect? STRINGCONSTANT ','
      //             STRINGCONSTANT
      bool HasSideEffect, AlignStack, AsmDialect;
      Lex.Lex();
      if (ParseOptionalToken(lltok::kw_sideeffect, HasSideEffect) ||
          ParseOptionalToken(lltok::kw_alignstack, AlignStack) ||
          ParseOptionalToken(lltok::kw_inteldialect, AsmDialect) ||
          ParseStringConstant(ID.StrVal) ||
          ParseToken(lltok::comma, "expected comma in inline asm expression") ||
          ParseToken(lltok::StringConstant, "expected constraint string"))
        return true;
      ID.StrVal2 = Lex.getStrVal();
      ID.UIntVal = unsigned(HasSideEffect) | (unsigned(AlignStack)<<1) |
        (unsigned(AsmDialect)<<2);
      ID.Kind = ValID::t_InlineAsm;
      return false;
    }
  
    case lltok::kw_blockaddress: {
      // ValID ::= 'blockaddress' '(' @foo ',' %bar ')'
      Lex.Lex();
  
      ValID Fn, Label;
  
      if (ParseToken(lltok::lparen, "expected '(' in block address expression") ||
          ParseValID(Fn) ||
          ParseToken(lltok::comma, "expected comma in block address expression")||
          ParseValID(Label) ||
          ParseToken(lltok::rparen, "expected ')' in block address expression"))
        return true;
  
      if (Fn.Kind != ValID::t_GlobalID && Fn.Kind != ValID::t_GlobalName)
        return Error(Fn.Loc, "expected function name in blockaddress");
      if (Label.Kind != ValID::t_LocalID && Label.Kind != ValID::t_LocalName)
        return Error(Label.Loc, "expected basic block name in blockaddress");
  
      // Try to find the function (but skip it if it's forward-referenced).
      GlobalValue *GV = nullptr;
      if (Fn.Kind == ValID::t_GlobalID) {
        if (Fn.UIntVal < NumberedVals.size())
          GV = NumberedVals[Fn.UIntVal];
      } else if (!ForwardRefVals.count(Fn.StrVal)) {
        GV = M->getNamedValue(Fn.StrVal);
      }
      Function *F = nullptr;
      if (GV) {
        // Confirm that it's actually a function with a definition.
        if (!isa<Function>(GV))
          return Error(Fn.Loc, "expected function name in blockaddress");
        F = cast<Function>(GV);
        if (F->isDeclaration())
          return Error(Fn.Loc, "cannot take blockaddress inside a declaration");
      }
  
      if (!F) {
        // Make a global variable as a placeholder for this reference.
        GlobalValue *&FwdRef = ForwardRefBlockAddresses[Fn][Label];
        if (!FwdRef)
          FwdRef = new GlobalVariable(*M, Type::getInt8Ty(Context), false,
                                      GlobalValue::InternalLinkage, nullptr, "");
        ID.ConstantVal = FwdRef;
        ID.Kind = ValID::t_Constant;
        return false;
      }
  
      // We found the function; now find the basic block.  Don't use PFS, since we
      // might be inside a constant expression.
      BasicBlock *BB;
      if (BlockAddressPFS && F == &BlockAddressPFS->getFunction()) {
        if (Label.Kind == ValID::t_LocalID)
          BB = BlockAddressPFS->GetBB(Label.UIntVal, Label.Loc);
        else
          BB = BlockAddressPFS->GetBB(Label.StrVal, Label.Loc);
        if (!BB)
          return Error(Label.Loc, "referenced value is not a basic block");
      } else {
        if (Label.Kind == ValID::t_LocalID)
          return Error(Label.Loc, "cannot take address of numeric label after "
                                  "the function is defined");
        BB = dyn_cast_or_null<BasicBlock>(
            F->getValueSymbolTable().lookup(Label.StrVal));
        if (!BB)
          return Error(Label.Loc, "referenced value is not a basic block");
      }
  
      ID.ConstantVal = BlockAddress::get(F, BB);
      ID.Kind = ValID::t_Constant;
      return false;
    }
  
    case lltok::kw_trunc:
    case lltok::kw_zext:
    case lltok::kw_sext:
    case lltok::kw_fptrunc:
    case lltok::kw_fpext:
    case lltok::kw_bitcast:
    case lltok::kw_addrspacecast:
    case lltok::kw_uitofp:
    case lltok::kw_sitofp:
    case lltok::kw_fptoui:
    case lltok::kw_fptosi:
    case lltok::kw_inttoptr:
    case lltok::kw_ptrtoint: {
      unsigned Opc = Lex.getUIntVal();
      Type *DestTy = nullptr;
      Constant *SrcVal;
      Lex.Lex();
      if (ParseToken(lltok::lparen, "expected '(' after constantexpr cast") ||
          ParseGlobalTypeAndValue(SrcVal) ||
          ParseToken(lltok::kw_to, "expected 'to' in constantexpr cast") ||
          ParseType(DestTy) ||
          ParseToken(lltok::rparen, "expected ')' at end of constantexpr cast"))
        return true;
      if (!CastInst::castIsValid((Instruction::CastOps)Opc, SrcVal, DestTy))
        return Error(ID.Loc, "invalid cast opcode for cast from '" +
                     getTypeString(SrcVal->getType()) + "' to '" +
                     getTypeString(DestTy) + "'");
      ID.ConstantVal = ConstantExpr::getCast((Instruction::CastOps)Opc,
                                                   SrcVal, DestTy);
      ID.Kind = ValID::t_Constant;
      return false;
    }
    case lltok::kw_extractvalue: {
      Lex.Lex();
      Constant *Val;
      SmallVector<unsigned, 4> Indices;
      if (ParseToken(lltok::lparen, "expected '(' in extractvalue constantexpr")||
          ParseGlobalTypeAndValue(Val) ||
          ParseIndexList(Indices) ||
          ParseToken(lltok::rparen, "expected ')' in extractvalue constantexpr"))
        return true;
  
      if (!Val->getType()->isAggregateType())
        return Error(ID.Loc, "extractvalue operand must be aggregate type");
      if (!ExtractValueInst::getIndexedType(Val->getType(), Indices))
        return Error(ID.Loc, "invalid indices for extractvalue");
      ID.ConstantVal = ConstantExpr::getExtractValue(Val, Indices);
      ID.Kind = ValID::t_Constant;
      return false;
    }
    case lltok::kw_insertvalue: {
      Lex.Lex();
      Constant *Val0, *Val1;
      SmallVector<unsigned, 4> Indices;
      if (ParseToken(lltok::lparen, "expected '(' in insertvalue constantexpr")||
          ParseGlobalTypeAndValue(Val0) ||
          ParseToken(lltok::comma, "expected comma in insertvalue constantexpr")||
          ParseGlobalTypeAndValue(Val1) ||
          ParseIndexList(Indices) ||
          ParseToken(lltok::rparen, "expected ')' in insertvalue constantexpr"))
        return true;
      if (!Val0->getType()->isAggregateType())
        return Error(ID.Loc, "insertvalue operand must be aggregate type");
      if (!ExtractValueInst::getIndexedType(Val0->getType(), Indices))
        return Error(ID.Loc, "invalid indices for insertvalue");
      ID.ConstantVal = ConstantExpr::getInsertValue(Val0, Val1, Indices);
      ID.Kind = ValID::t_Constant;
      return false;
    }
    case lltok::kw_icmp:
    case lltok::kw_fcmp: {
      unsigned PredVal, Opc = Lex.getUIntVal();
      Constant *Val0, *Val1;
      Lex.Lex();
      if (ParseCmpPredicate(PredVal, Opc) ||
          ParseToken(lltok::lparen, "expected '(' in compare constantexpr") ||
          ParseGlobalTypeAndValue(Val0) ||
          ParseToken(lltok::comma, "expected comma in compare constantexpr") ||
          ParseGlobalTypeAndValue(Val1) ||
          ParseToken(lltok::rparen, "expected ')' in compare constantexpr"))
        return true;
  
      if (Val0->getType() != Val1->getType())
        return Error(ID.Loc, "compare operands must have the same type");
  
      CmpInst::Predicate Pred = (CmpInst::Predicate)PredVal;
  
      if (Opc == Instruction::FCmp) {
        if (!Val0->getType()->isFPOrFPVectorTy())
          return Error(ID.Loc, "fcmp requires floating point operands");
        ID.ConstantVal = ConstantExpr::getFCmp(Pred, Val0, Val1);
      } else {
        assert(Opc == Instruction::ICmp && "Unexpected opcode for CmpInst!");
        if (!Val0->getType()->isIntOrIntVectorTy() &&
            !Val0->getType()->getScalarType()->isPointerTy())
          return Error(ID.Loc, "icmp requires pointer or integer operands");
        ID.ConstantVal = ConstantExpr::getICmp(Pred, Val0, Val1);
      }
      ID.Kind = ValID::t_Constant;
      return false;
    }
  
    // Binary Operators.
    case lltok::kw_add:
    case lltok::kw_fadd:
    case lltok::kw_sub:
    case lltok::kw_fsub:
    case lltok::kw_mul:
    case lltok::kw_fmul:
    case lltok::kw_udiv:
    case lltok::kw_sdiv:
    case lltok::kw_fdiv:
    case lltok::kw_urem:
    case lltok::kw_srem:
    case lltok::kw_frem:
    case lltok::kw_shl:
    case lltok::kw_lshr:
    case lltok::kw_ashr: {
      bool NUW = false;
      bool NSW = false;
      bool Exact = false;
      unsigned Opc = Lex.getUIntVal();
      Constant *Val0, *Val1;
      Lex.Lex();
      LocTy ModifierLoc = Lex.getLoc();
      if (Opc == Instruction::Add || Opc == Instruction::Sub ||
          Opc == Instruction::Mul || Opc == Instruction::Shl) {
        if (EatIfPresent(lltok::kw_nuw))
          NUW = true;
        if (EatIfPresent(lltok::kw_nsw)) {
          NSW = true;
          if (EatIfPresent(lltok::kw_nuw))
            NUW = true;
        }
      } else if (Opc == Instruction::SDiv || Opc == Instruction::UDiv ||
                 Opc == Instruction::LShr || Opc == Instruction::AShr) {
        if (EatIfPresent(lltok::kw_exact))
          Exact = true;
      }
      if (ParseToken(lltok::lparen, "expected '(' in binary constantexpr") ||
          ParseGlobalTypeAndValue(Val0) ||
          ParseToken(lltok::comma, "expected comma in binary constantexpr") ||
          ParseGlobalTypeAndValue(Val1) ||
          ParseToken(lltok::rparen, "expected ')' in binary constantexpr"))
        return true;
      if (Val0->getType() != Val1->getType())
        return Error(ID.Loc, "operands of constexpr must have same type");
      if (!Val0->getType()->isIntOrIntVectorTy()) {
        if (NUW)
          return Error(ModifierLoc, "nuw only applies to integer operations");
        if (NSW)
          return Error(ModifierLoc, "nsw only applies to integer operations");
      }
      // Check that the type is valid for the operator.
      switch (Opc) {
      case Instruction::Add:
      case Instruction::Sub:
      case Instruction::Mul:
      case Instruction::UDiv:
      case Instruction::SDiv:
      case Instruction::URem:
      case Instruction::SRem:
      case Instruction::Shl:
      case Instruction::AShr:
      case Instruction::LShr:
        if (!Val0->getType()->isIntOrIntVectorTy())
          return Error(ID.Loc, "constexpr requires integer operands");
        break;
      case Instruction::FAdd:
      case Instruction::FSub:
      case Instruction::FMul:
      case Instruction::FDiv:
      case Instruction::FRem:
        if (!Val0->getType()->isFPOrFPVectorTy())
          return Error(ID.Loc, "constexpr requires fp operands");
        break;
      default: llvm_unreachable("Unknown binary operator!");
      }
      unsigned Flags = 0;
      if (NUW)   Flags |= OverflowingBinaryOperator::NoUnsignedWrap;
      if (NSW)   Flags |= OverflowingBinaryOperator::NoSignedWrap;
      if (Exact) Flags |= PossiblyExactOperator::IsExact;
      Constant *C = ConstantExpr::get(Opc, Val0, Val1, Flags);
      ID.ConstantVal = C;
      ID.Kind = ValID::t_Constant;
      return false;
    }
  
    // Logical Operations
    case lltok::kw_and:
    case lltok::kw_or:
    case lltok::kw_xor: {
      unsigned Opc = Lex.getUIntVal();
      Constant *Val0, *Val1;
      Lex.Lex();
      if (ParseToken(lltok::lparen, "expected '(' in logical constantexpr") ||
          ParseGlobalTypeAndValue(Val0) ||
          ParseToken(lltok::comma, "expected comma in logical constantexpr") ||
          ParseGlobalTypeAndValue(Val1) ||
          ParseToken(lltok::rparen, "expected ')' in logical constantexpr"))
        return true;
      if (Val0->getType() != Val1->getType())
        return Error(ID.Loc, "operands of constexpr must have same type");
      if (!Val0->getType()->isIntOrIntVectorTy())
        return Error(ID.Loc,
                     "constexpr requires integer or integer vector operands");
      ID.ConstantVal = ConstantExpr::get(Opc, Val0, Val1);
      ID.Kind = ValID::t_Constant;
      return false;
    }
  
    case lltok::kw_getelementptr:
    case lltok::kw_shufflevector:
    case lltok::kw_insertelement:
    case lltok::kw_extractelement:
    case lltok::kw_select: {
      unsigned Opc = Lex.getUIntVal();
      SmallVector<Constant*, 16> Elts;
      bool InBounds = false;
      Lex.Lex();
      if (Opc == Instruction::GetElementPtr)
        InBounds = EatIfPresent(lltok::kw_inbounds);
      if (ParseToken(lltok::lparen, "expected '(' in constantexpr") ||
          ParseGlobalValueVector(Elts) ||
          ParseToken(lltok::rparen, "expected ')' in constantexpr"))
        return true;
  
      if (Opc == Instruction::GetElementPtr) {
        if (Elts.size() == 0 ||
            !Elts[0]->getType()->getScalarType()->isPointerTy())
          return Error(ID.Loc, "getelementptr requires pointer operand");
  
        ArrayRef<Constant *> Indices(Elts.begin() + 1, Elts.end());
        if (!GetElementPtrInst::getIndexedType(Elts[0]->getType(), Indices))
          return Error(ID.Loc, "invalid indices for getelementptr");
        ID.ConstantVal = ConstantExpr::getGetElementPtr(Elts[0], Indices,
                                                        InBounds);
      } else if (Opc == Instruction::Select) {
        if (Elts.size() != 3)
          return Error(ID.Loc, "expected three operands to select");
        if (const char *Reason = SelectInst::areInvalidOperands(Elts[0], Elts[1],
                                                                Elts[2]))
          return Error(ID.Loc, Reason);
        ID.ConstantVal = ConstantExpr::getSelect(Elts[0], Elts[1], Elts[2]);
      } else if (Opc == Instruction::ShuffleVector) {
        if (Elts.size() != 3)
          return Error(ID.Loc, "expected three operands to shufflevector");
        if (!ShuffleVectorInst::isValidOperands(Elts[0], Elts[1], Elts[2]))
          return Error(ID.Loc, "invalid operands to shufflevector");
        ID.ConstantVal =
                   ConstantExpr::getShuffleVector(Elts[0], Elts[1],Elts[2]);
      } else if (Opc == Instruction::ExtractElement) {
        if (Elts.size() != 2)
          return Error(ID.Loc, "expected two operands to extractelement");
        if (!ExtractElementInst::isValidOperands(Elts[0], Elts[1]))
          return Error(ID.Loc, "invalid extractelement operands");
        ID.ConstantVal = ConstantExpr::getExtractElement(Elts[0], Elts[1]);
      } else {
        assert(Opc == Instruction::InsertElement && "Unknown opcode");
        if (Elts.size() != 3)
        return Error(ID.Loc, "expected three operands to insertelement");
        if (!InsertElementInst::isValidOperands(Elts[0], Elts[1], Elts[2]))
          return Error(ID.Loc, "invalid insertelement operands");
        ID.ConstantVal =
                   ConstantExpr::getInsertElement(Elts[0], Elts[1],Elts[2]);
      }
  
      ID.Kind = ValID::t_Constant;
      return false;
    }
    }
  
    Lex.Lex();
    return false;
  }
  
  /// ParseGlobalValue - Parse a global value with the specified type.
  bool LLParser::ParseGlobalValue(Type *Ty, Constant *&C) {
    C = nullptr;
    ValID ID;
    Value *V = nullptr;
    bool Parsed = ParseValID(ID) ||
                  ConvertValIDToValue(Ty, ID, V, nullptr);
    if (V && !(C = dyn_cast<Constant>(V)))
      return Error(ID.Loc, "global values must be constants");
    return Parsed;
  }
  
  bool LLParser::ParseGlobalTypeAndValue(Constant *&V) {
    Type *Ty = nullptr;
    return ParseType(Ty) ||
           ParseGlobalValue(Ty, V);
  }
  
  bool LLParser::parseOptionalComdat(StringRef GlobalName, Comdat *&C) {
    C = nullptr;
  
    LocTy KwLoc = Lex.getLoc();
    if (!EatIfPresent(lltok::kw_comdat))
      return false;
  
    if (EatIfPresent(lltok::lparen)) {
      if (Lex.getKind() != lltok::ComdatVar)
        return TokError("expected comdat variable");
      C = getComdat(Lex.getStrVal(), Lex.getLoc());
      Lex.Lex();
      if (ParseToken(lltok::rparen, "expected ')' after comdat var"))
        return true;
    } else {
      if (GlobalName.empty())
        return TokError("comdat cannot be unnamed");
      C = getComdat(GlobalName, KwLoc);
    }
  
    return false;
  }
  
  /// ParseGlobalValueVector
  ///   ::= /*empty*/
  ///   ::= TypeAndValue (',' TypeAndValue)*
  bool LLParser::ParseGlobalValueVector(SmallVectorImpl<Constant *> &Elts) {
    // Empty list.
    if (Lex.getKind() == lltok::rbrace ||
        Lex.getKind() == lltok::rsquare ||
        Lex.getKind() == lltok::greater ||
        Lex.getKind() == lltok::rparen)
      return false;
  
    Constant *C;
    if (ParseGlobalTypeAndValue(C)) return true;
    Elts.push_back(C);
  
    while (EatIfPresent(lltok::comma)) {
      if (ParseGlobalTypeAndValue(C)) return true;
      Elts.push_back(C);
    }
  
    return false;
  }
  
  bool LLParser::ParseMDTuple(MDNode *&MD, bool IsDistinct) {
    SmallVector<Metadata *, 16> Elts;
    if (ParseMDNodeVector(Elts))
      return true;
  
    MD = (IsDistinct ? MDTuple::getDistinct : MDTuple::get)(Context, Elts);
    return false;
  }
  
  /// MDNode:
  ///  ::= !{ ... }
  ///  ::= !7
  ///  ::= !MDLocation(...)
  bool LLParser::ParseMDNode(MDNode *&N) {
    if (Lex.getKind() == lltok::MetadataVar)
      return ParseSpecializedMDNode(N);
  
    return ParseToken(lltok::exclaim, "expected '!' here") ||
           ParseMDNodeTail(N);
  }
  
  bool LLParser::ParseMDNodeTail(MDNode *&N) {
    // !{ ... }
    if (Lex.getKind() == lltok::lbrace)
      return ParseMDTuple(N);
  
    // !42
    return ParseMDNodeID(N);
  }
  
  bool LLParser::ParseMDField(LocTy Loc, StringRef Name,
                              MDUnsignedField<uint32_t> &Result) {
    if (Result.Seen)
      return Error(Loc,
                   "field '" + Name + "' cannot be specified more than once");
  
    if (Lex.getKind() != lltok::APSInt || Lex.getAPSIntVal().isSigned())
      return TokError("expected unsigned integer");
    uint64_t Val64 = Lex.getAPSIntVal().getLimitedValue(Result.Max + 1ull);
  
    if (Val64 > Result.Max)
      return TokError("value for '" + Name + "' too large, limit is " +
                      Twine(Result.Max));
    Result.assign(Val64);
    Lex.Lex();
    return false;
  }
  
  bool LLParser::ParseMDField(LocTy Loc, StringRef Name, MDField &Result) {
    if (Result.Seen)
      return Error(Loc,
                   "field '" + Name + "' cannot be specified more than once");
  
    Metadata *MD;
    if (ParseMetadata(MD, nullptr))
      return true;
  
    Result.assign(MD);
    return false;
  }
  
  template <class ParserTy>
  bool LLParser::ParseMDFieldsImpl(ParserTy parseField) {
    assert(Lex.getKind() == lltok::MetadataVar && "Expected metadata type name");
    Lex.Lex();
  
    if (ParseToken(lltok::lparen, "expected '(' here"))
      return true;
    if (EatIfPresent(lltok::rparen))
      return false;
  
    do {
      if (Lex.getKind() != lltok::LabelStr)
        return TokError("expected field label here");
  
      if (parseField())
        return true;
    } while (EatIfPresent(lltok::comma));
  
    return ParseToken(lltok::rparen, "expected ')' here");
  }
  
  bool LLParser::ParseSpecializedMDNode(MDNode *&N, bool IsDistinct) {
    assert(Lex.getKind() == lltok::MetadataVar && "Expected metadata type name");
  #define DISPATCH_TO_PARSER(CLASS)                                              \
    if (Lex.getStrVal() == #CLASS)                                               \
      return Parse##CLASS(N, IsDistinct);
  
    DISPATCH_TO_PARSER(MDLocation);
  #undef DISPATCH_TO_PARSER
  
    return TokError("expected metadata type");
  }
  
  #define PARSE_MD_FIELD(NAME)                                                   \
    do {                                                                         \
      if (Lex.getStrVal() == #NAME) {                                            \
        LocTy Loc = Lex.getLoc();                                                \
        Lex.Lex();                                                               \
        if (ParseMDField(Loc, #NAME, NAME))                                      \
          return true;                                                           \
        return false;                                                            \
      }                                                                          \
    } while (0)
  
  /// ParseMDLocationFields:
  ///   ::= !MDLocation(line: 43, column: 8, scope: !5, inlinedAt: !6)
  bool LLParser::ParseMDLocation(MDNode *&Result, bool IsDistinct) {
    MDUnsignedField<uint32_t> line(0, ~0u >> 8);
    MDUnsignedField<uint32_t> column(0, ~0u >> 24);
    MDField scope;
    MDField inlinedAt;
    if (ParseMDFieldsImpl([&]() -> bool {
          PARSE_MD_FIELD(line);
          PARSE_MD_FIELD(column);
          PARSE_MD_FIELD(scope);
          PARSE_MD_FIELD(inlinedAt);
          return TokError(Twine("invalid field '") + Lex.getStrVal() + "'");
        }))
      return true;
  
    if (!scope.Seen)
      return TokError("missing required field 'scope'");
  
    auto get = (IsDistinct ? MDLocation::getDistinct : MDLocation::get);
    Result = get(Context, line.Val, column.Val, scope.Val, inlinedAt.Val);
    return false;
  }
  #undef PARSE_MD_FIELD
  
  /// ParseMetadataAsValue
  ///  ::= metadata i32 %local
  ///  ::= metadata i32 @global
  ///  ::= metadata i32 7
  ///  ::= metadata !0
  ///  ::= metadata !{...}
  ///  ::= metadata !"string"
  bool LLParser::ParseMetadataAsValue(Value *&V, PerFunctionState &PFS) {
    // Note: the type 'metadata' has already been parsed.
    Metadata *MD;
    if (ParseMetadata(MD, &PFS))
      return true;
  
    V = MetadataAsValue::get(Context, MD);
    return false;
  }
  
  /// ParseValueAsMetadata
  ///  ::= i32 %local
  ///  ::= i32 @global
  ///  ::= i32 7
  bool LLParser::ParseValueAsMetadata(Metadata *&MD, PerFunctionState *PFS) {
    Type *Ty;
    LocTy Loc;
    if (ParseType(Ty, "expected metadata operand", Loc))
      return true;
    if (Ty->isMetadataTy())
      return Error(Loc, "invalid metadata-value-metadata roundtrip");
  
    Value *V;
    if (ParseValue(Ty, V, PFS))
      return true;
  
    MD = ValueAsMetadata::get(V);
    return false;
  }
  
  /// ParseMetadata
  ///  ::= i32 %local
  ///  ::= i32 @global
  ///  ::= i32 7
  ///  ::= !42
  ///  ::= !{...}
  ///  ::= !"string"
  ///  ::= !MDLocation(...)
  bool LLParser::ParseMetadata(Metadata *&MD, PerFunctionState *PFS) {
    if (Lex.getKind() == lltok::MetadataVar) {
      MDNode *N;
      if (ParseSpecializedMDNode(N))
        return true;
      MD = N;
      return false;
    }
  
    // ValueAsMetadata:
    // <type> <value>
    if (Lex.getKind() != lltok::exclaim)
      return ParseValueAsMetadata(MD, PFS);
  
    // '!'.
    assert(Lex.getKind() == lltok::exclaim && "Expected '!' here");
    Lex.Lex();
  
    // MDString:
    //   ::= '!' STRINGCONSTANT
    if (Lex.getKind() == lltok::StringConstant) {
      MDString *S;
      if (ParseMDString(S))
        return true;
      MD = S;
      return false;
    }
  
    // MDNode:
    // !{ ... }
    // !7
    MDNode *N;
    if (ParseMDNodeTail(N))
      return true;
    MD = N;
    return false;
  }
  
  
  //===----------------------------------------------------------------------===//
  // Function Parsing.
  //===----------------------------------------------------------------------===//
  
  bool LLParser::ConvertValIDToValue(Type *Ty, ValID &ID, Value *&V,
                                     PerFunctionState *PFS) {
    if (Ty->isFunctionTy())
      return Error(ID.Loc, "functions are not values, refer to them as pointers");
  
    switch (ID.Kind) {
    case ValID::t_LocalID:
      if (!PFS) return Error(ID.Loc, "invalid use of function-local name");
      V = PFS->GetVal(ID.UIntVal, Ty, ID.Loc);
      return V == nullptr;
    case ValID::t_LocalName:
      if (!PFS) return Error(ID.Loc, "invalid use of function-local name");
      V = PFS->GetVal(ID.StrVal, Ty, ID.Loc);
      return V == nullptr;
    case ValID::t_InlineAsm: {
      PointerType *PTy = dyn_cast<PointerType>(Ty);
      FunctionType *FTy =
        PTy ? dyn_cast<FunctionType>(PTy->getElementType()) : nullptr;
      if (!FTy || !InlineAsm::Verify(FTy, ID.StrVal2))
        return Error(ID.Loc, "invalid type for inline asm constraint string");
      V = InlineAsm::get(FTy, ID.StrVal, ID.StrVal2, ID.UIntVal&1,
                         (ID.UIntVal>>1)&1, (InlineAsm::AsmDialect(ID.UIntVal>>2)));
      return false;
    }
    case ValID::t_GlobalName:
      V = GetGlobalVal(ID.StrVal, Ty, ID.Loc);
      return V == nullptr;
    case ValID::t_GlobalID:
      V = GetGlobalVal(ID.UIntVal, Ty, ID.Loc);
      return V == nullptr;
    case ValID::t_APSInt:
      if (!Ty->isIntegerTy())
        return Error(ID.Loc, "integer constant must have integer type");
      ID.APSIntVal = ID.APSIntVal.extOrTrunc(Ty->getPrimitiveSizeInBits());
      V = ConstantInt::get(Context, ID.APSIntVal);
      return false;
    case ValID::t_APFloat:
      if (!Ty->isFloatingPointTy() ||
          !ConstantFP::isValueValidForType(Ty, ID.APFloatVal))
        return Error(ID.Loc, "floating point constant invalid for type");
  
      // The lexer has no type info, so builds all half, float, and double FP
      // constants as double.  Fix this here.  Long double does not need this.
      if (&ID.APFloatVal.getSemantics() == &APFloat::IEEEdouble) {
        bool Ignored;
        if (Ty->isHalfTy())
          ID.APFloatVal.convert(APFloat::IEEEhalf, APFloat::rmNearestTiesToEven,
                                &Ignored);
        else if (Ty->isFloatTy())
          ID.APFloatVal.convert(APFloat::IEEEsingle, APFloat::rmNearestTiesToEven,
                                &Ignored);
      }
      V = ConstantFP::get(Context, ID.APFloatVal);
  
      if (V->getType() != Ty)
        return Error(ID.Loc, "floating point constant does not have type '" +
                     getTypeString(Ty) + "'");
  
      return false;
    case ValID::t_Null:
      if (!Ty->isPointerTy())
        return Error(ID.Loc, "null must be a pointer type");
      V = ConstantPointerNull::get(cast<PointerType>(Ty));
      return false;
    case ValID::t_Undef:
      // FIXME: LabelTy should not be a first-class type.
      if (!Ty->isFirstClassType() || Ty->isLabelTy())
        return Error(ID.Loc, "invalid type for undef constant");
      V = UndefValue::get(Ty);
      return false;
    case ValID::t_EmptyArray:
      if (!Ty->isArrayTy() || cast<ArrayType>(Ty)->getNumElements() != 0)
        return Error(ID.Loc, "invalid empty array initializer");
      V = UndefValue::get(Ty);
      return false;
    case ValID::t_Zero:
      // FIXME: LabelTy should not be a first-class type.
      if (!Ty->isFirstClassType() || Ty->isLabelTy())
        return Error(ID.Loc, "invalid type for null constant");
      V = Constant::getNullValue(Ty);
      return false;
    case ValID::t_Constant:
      if (ID.ConstantVal->getType() != Ty)
        return Error(ID.Loc, "constant expression type mismatch");
  
      V = ID.ConstantVal;
      return false;
    case ValID::t_ConstantStruct:
    case ValID::t_PackedConstantStruct:
      if (StructType *ST = dyn_cast<StructType>(Ty)) {
        if (ST->getNumElements() != ID.UIntVal)
          return Error(ID.Loc,
                       "initializer with struct type has wrong # elements");
        if (ST->isPacked() != (ID.Kind == ValID::t_PackedConstantStruct))
          return Error(ID.Loc, "packed'ness of initializer and type don't match");
  
        // Verify that the elements are compatible with the structtype.
        for (unsigned i = 0, e = ID.UIntVal; i != e; ++i)
          if (ID.ConstantStructElts[i]->getType() != ST->getElementType(i))
            return Error(ID.Loc, "element " + Twine(i) +
                      " of struct initializer doesn't match struct element type");
  
        V = ConstantStruct::get(ST, makeArrayRef(ID.ConstantStructElts,
                                                 ID.UIntVal));
      } else
        return Error(ID.Loc, "constant expression type mismatch");
      return false;
    }
    llvm_unreachable("Invalid ValID");
  }
  
  bool LLParser::ParseValue(Type *Ty, Value *&V, PerFunctionState *PFS) {
    V = nullptr;
    ValID ID;
    return ParseValID(ID, PFS) ||
           ConvertValIDToValue(Ty, ID, V, PFS);
  }
  
  bool LLParser::ParseTypeAndValue(Value *&V, PerFunctionState *PFS) {
    Type *Ty = nullptr;
    return ParseType(Ty) ||
           ParseValue(Ty, V, PFS);
  }
  
  bool LLParser::ParseTypeAndBasicBlock(BasicBlock *&BB, LocTy &Loc,
                                        PerFunctionState &PFS) {
    Value *V;
    Loc = Lex.getLoc();
    if (ParseTypeAndValue(V, PFS)) return true;
    if (!isa<BasicBlock>(V))
      return Error(Loc, "expected a basic block");
    BB = cast<BasicBlock>(V);
    return false;
  }
  
  
  /// FunctionHeader
  ///   ::= OptionalLinkage OptionalVisibility OptionalCallingConv OptRetAttrs
  ///       OptUnnamedAddr Type GlobalName '(' ArgList ')' OptFuncAttrs OptSection
  ///       OptionalAlign OptGC OptionalPrefix OptionalPrologue
  bool LLParser::ParseFunctionHeader(Function *&Fn, bool isDefine) {
    // Parse the linkage.
    LocTy LinkageLoc = Lex.getLoc();
    unsigned Linkage;
  
    unsigned Visibility;
    unsigned DLLStorageClass;
    AttrBuilder RetAttrs;
    unsigned CC;
    Type *RetType = nullptr;
    LocTy RetTypeLoc = Lex.getLoc();
    if (ParseOptionalLinkage(Linkage) ||
        ParseOptionalVisibility(Visibility) ||
        ParseOptionalDLLStorageClass(DLLStorageClass) ||
        ParseOptionalCallingConv(CC) ||
        ParseOptionalReturnAttrs(RetAttrs) ||
        ParseType(RetType, RetTypeLoc, true /*void allowed*/))
      return true;
  
    // Verify that the linkage is ok.
    switch ((GlobalValue::LinkageTypes)Linkage) {
    case GlobalValue::ExternalLinkage:
      break; // always ok.
    case GlobalValue::ExternalWeakLinkage:
      if (isDefine)
        return Error(LinkageLoc, "invalid linkage for function definition");
      break;
    case GlobalValue::PrivateLinkage:
    case GlobalValue::InternalLinkage:
    case GlobalValue::AvailableExternallyLinkage:
    case GlobalValue::LinkOnceAnyLinkage:
    case GlobalValue::LinkOnceODRLinkage:
    case GlobalValue::WeakAnyLinkage:
    case GlobalValue::WeakODRLinkage:
      if (!isDefine)
        return Error(LinkageLoc, "invalid linkage for function declaration");
      break;
    case GlobalValue::AppendingLinkage:
    case GlobalValue::CommonLinkage:
      return Error(LinkageLoc, "invalid function linkage type");
    }
  
    if (!isValidVisibilityForLinkage(Visibility, Linkage))
      return Error(LinkageLoc,
                   "symbol with local linkage must have default visibility");
  
    if (!FunctionType::isValidReturnType(RetType))
      return Error(RetTypeLoc, "invalid function return type");
  
    LocTy NameLoc = Lex.getLoc();
  
    std::string FunctionName;
    if (Lex.getKind() == lltok::GlobalVar) {
      FunctionName = Lex.getStrVal();
    } else if (Lex.getKind() == lltok::GlobalID) {     // @42 is ok.
      unsigned NameID = Lex.getUIntVal();
  
      if (NameID != NumberedVals.size())
        return TokError("function expected to be numbered '%" +
                        Twine(NumberedVals.size()) + "'");
    } else {
      return TokError("expected function name");
    }
  
    Lex.Lex();
  
    if (Lex.getKind() != lltok::lparen)
      return TokError("expected '(' in function argument list");
  
    SmallVector<ArgInfo, 8> ArgList;
    bool isVarArg;
    AttrBuilder FuncAttrs;
    std::vector<unsigned> FwdRefAttrGrps;
    LocTy BuiltinLoc;
    std::string Section;
    unsigned Alignment;
    std::string GC;
    bool UnnamedAddr;
    LocTy UnnamedAddrLoc;
    Constant *Prefix = nullptr;
    Constant *Prologue = nullptr;
    Comdat *C;
  
    if (ParseArgumentList(ArgList, isVarArg) ||
        ParseOptionalToken(lltok::kw_unnamed_addr, UnnamedAddr,
                           &UnnamedAddrLoc) ||
        ParseFnAttributeValuePairs(FuncAttrs, FwdRefAttrGrps, false,
                                   BuiltinLoc) ||
        (EatIfPresent(lltok::kw_section) &&
         ParseStringConstant(Section)) ||
        parseOptionalComdat(FunctionName, C) ||
        ParseOptionalAlignment(Alignment) ||
        (EatIfPresent(lltok::kw_gc) &&
         ParseStringConstant(GC)) ||
        (EatIfPresent(lltok::kw_prefix) &&
         ParseGlobalTypeAndValue(Prefix)) ||
        (EatIfPresent(lltok::kw_prologue) &&
         ParseGlobalTypeAndValue(Prologue)))
      return true;
  
    if (FuncAttrs.contains(Attribute::Builtin))
      return Error(BuiltinLoc, "'builtin' attribute not valid on function");
  
    // If the alignment was parsed as an attribute, move to the alignment field.
    if (FuncAttrs.hasAlignmentAttr()) {
      Alignment = FuncAttrs.getAlignment();
      FuncAttrs.removeAttribute(Attribute::Alignment);
    }
  
    // Okay, if we got here, the function is syntactically valid.  Convert types
    // and do semantic checks.
    std::vector<Type*> ParamTypeList;
    SmallVector<AttributeSet, 8> Attrs;
  
    if (RetAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::ReturnIndex,
                                        RetAttrs));
  
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i) {
      ParamTypeList.push_back(ArgList[i].Ty);
      if (ArgList[i].Attrs.hasAttributes(i + 1)) {
        AttrBuilder B(ArgList[i].Attrs, i + 1);
        Attrs.push_back(AttributeSet::get(RetType->getContext(), i + 1, B));
      }
    }
  
    if (FuncAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::FunctionIndex,
                                        FuncAttrs));
  
    AttributeSet PAL = AttributeSet::get(Context, Attrs);
  
    if (PAL.hasAttribute(1, Attribute::StructRet) && !RetType->isVoidTy())
      return Error(RetTypeLoc, "functions with 'sret' argument must return void");
  
    FunctionType *FT =
      FunctionType::get(RetType, ParamTypeList, isVarArg);
    PointerType *PFT = PointerType::getUnqual(FT);
  
    Fn = nullptr;
    if (!FunctionName.empty()) {
      // If this was a definition of a forward reference, remove the definition
      // from the forward reference table and fill in the forward ref.
      std::map<std::string, std::pair<GlobalValue*, LocTy> >::iterator FRVI =
        ForwardRefVals.find(FunctionName);
      if (FRVI != ForwardRefVals.end()) {
        Fn = M->getFunction(FunctionName);
        if (!Fn)
          return Error(FRVI->second.second, "invalid forward reference to "
                       "function as global value!");
        if (Fn->getType() != PFT)
          return Error(FRVI->second.second, "invalid forward reference to "
                       "function '" + FunctionName + "' with wrong type!");
  
        ForwardRefVals.erase(FRVI);
      } else if ((Fn = M->getFunction(FunctionName))) {
        // Reject redefinitions.
        return Error(NameLoc, "invalid redefinition of function '" +
                     FunctionName + "'");
      } else if (M->getNamedValue(FunctionName)) {
        return Error(NameLoc, "redefinition of function '@" + FunctionName + "'");
      }
  
    } else {
      // If this is a definition of a forward referenced function, make sure the
      // types agree.
      std::map<unsigned, std::pair<GlobalValue*, LocTy> >::iterator I
        = ForwardRefValIDs.find(NumberedVals.size());
      if (I != ForwardRefValIDs.end()) {
        Fn = cast<Function>(I->second.first);
        if (Fn->getType() != PFT)
          return Error(NameLoc, "type of definition and forward reference of '@" +
                       Twine(NumberedVals.size()) + "' disagree");
        ForwardRefValIDs.erase(I);
      }
    }
  
    if (!Fn)
      Fn = Function::Create(FT, GlobalValue::ExternalLinkage, FunctionName, M);
    else // Move the forward-reference to the correct spot in the module.
      M->getFunctionList().splice(M->end(), M->getFunctionList(), Fn);
  
    if (FunctionName.empty())
      NumberedVals.push_back(Fn);
  
    Fn->setLinkage((GlobalValue::LinkageTypes)Linkage);
    Fn->setVisibility((GlobalValue::VisibilityTypes)Visibility);
    Fn->setDLLStorageClass((GlobalValue::DLLStorageClassTypes)DLLStorageClass);
    Fn->setCallingConv(CC);
    Fn->setAttributes(PAL);
    Fn->setUnnamedAddr(UnnamedAddr);
    Fn->setAlignment(Alignment);
    Fn->setSection(Section);
    Fn->setComdat(C);
    if (!GC.empty()) Fn->setGC(GC.c_str());
    Fn->setPrefixData(Prefix);
    Fn->setPrologueData(Prologue);
    ForwardRefAttrGroups[Fn] = FwdRefAttrGrps;
  
    // Add all of the arguments we parsed to the function.
    Function::arg_iterator ArgIt = Fn->arg_begin();
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i, ++ArgIt) {
      // If the argument has a name, insert it into the argument symbol table.
      if (ArgList[i].Name.empty()) continue;
  
      // Set the name, if it conflicted, it will be auto-renamed.
      ArgIt->setName(ArgList[i].Name);
  
      if (ArgIt->getName() != ArgList[i].Name)
        return Error(ArgList[i].Loc, "redefinition of argument '%" +
                     ArgList[i].Name + "'");
    }
  
    if (isDefine)
      return false;
  
    // Check the declaration has no block address forward references.
    ValID ID;
    if (FunctionName.empty()) {
      ID.Kind = ValID::t_GlobalID;
      ID.UIntVal = NumberedVals.size() - 1;
    } else {
      ID.Kind = ValID::t_GlobalName;
      ID.StrVal = FunctionName;
    }
    auto Blocks = ForwardRefBlockAddresses.find(ID);
    if (Blocks != ForwardRefBlockAddresses.end())
      return Error(Blocks->first.Loc,
                   "cannot take blockaddress inside a declaration");
    return false;
  }
  
  bool LLParser::PerFunctionState::resolveForwardRefBlockAddresses() {
    ValID ID;
    if (FunctionNumber == -1) {
      ID.Kind = ValID::t_GlobalName;
      ID.StrVal = F.getName();
    } else {
      ID.Kind = ValID::t_GlobalID;
      ID.UIntVal = FunctionNumber;
    }
  
    auto Blocks = P.ForwardRefBlockAddresses.find(ID);
    if (Blocks == P.ForwardRefBlockAddresses.end())
      return false;
  
    for (const auto &I : Blocks->second) {
      const ValID &BBID = I.first;
      GlobalValue *GV = I.second;
  
      assert((BBID.Kind == ValID::t_LocalID || BBID.Kind == ValID::t_LocalName) &&
             "Expected local id or name");
      BasicBlock *BB;
      if (BBID.Kind == ValID::t_LocalName)
        BB = GetBB(BBID.StrVal, BBID.Loc);
      else
        BB = GetBB(BBID.UIntVal, BBID.Loc);
      if (!BB)
        return P.Error(BBID.Loc, "referenced value is not a basic block");
  
      GV->replaceAllUsesWith(BlockAddress::get(&F, BB));
      GV->eraseFromParent();
    }
  
    P.ForwardRefBlockAddresses.erase(Blocks);
    return false;
  }
  
  /// ParseFunctionBody
  ///   ::= '{' BasicBlock+ UseListOrderDirective* '}'
  bool LLParser::ParseFunctionBody(Function &Fn) {
    if (Lex.getKind() != lltok::lbrace)
      return TokError("expected '{' in function body");
    Lex.Lex();  // eat the {.
  
    int FunctionNumber = -1;
    if (!Fn.hasName()) FunctionNumber = NumberedVals.size()-1;
  
    PerFunctionState PFS(*this, Fn, FunctionNumber);
  
    // Resolve block addresses and allow basic blocks to be forward-declared
    // within this function.
    if (PFS.resolveForwardRefBlockAddresses())
      return true;
    SaveAndRestore<PerFunctionState *> ScopeExit(BlockAddressPFS, &PFS);
  
    // We need at least one basic block.
    if (Lex.getKind() == lltok::rbrace || Lex.getKind() == lltok::kw_uselistorder)
      return TokError("function body requires at least one basic block");
  
    while (Lex.getKind() != lltok::rbrace &&
           Lex.getKind() != lltok::kw_uselistorder)
      if (ParseBasicBlock(PFS)) return true;
  
    while (Lex.getKind() != lltok::rbrace)
      if (ParseUseListOrder(&PFS))
        return true;
  
    // Eat the }.
    Lex.Lex();
  
    // Verify function is ok.
    return PFS.FinishFunction();
  }
  
  /// ParseBasicBlock
  ///   ::= LabelStr? Instruction*
  bool LLParser::ParseBasicBlock(PerFunctionState &PFS) {
    // If this basic block starts out with a name, remember it.
    std::string Name;
    LocTy NameLoc = Lex.getLoc();
    if (Lex.getKind() == lltok::LabelStr) {
      Name = Lex.getStrVal();
      Lex.Lex();
    }
  
    BasicBlock *BB = PFS.DefineBB(Name, NameLoc);
    if (!BB) return true;
  
    std::string NameStr;
  
    // Parse the instructions in this block until we get a terminator.
    Instruction *Inst;
    do {
      // This instruction may have three possibilities for a name: a) none
      // specified, b) name specified "%foo =", c) number specified: "%4 =".
      LocTy NameLoc = Lex.getLoc();
      int NameID = -1;
      NameStr = "";
  
      if (Lex.getKind() == lltok::LocalVarID) {
        NameID = Lex.getUIntVal();
        Lex.Lex();
        if (ParseToken(lltok::equal, "expected '=' after instruction id"))
          return true;
      } else if (Lex.getKind() == lltok::LocalVar) {
        NameStr = Lex.getStrVal();
        Lex.Lex();
        if (ParseToken(lltok::equal, "expected '=' after instruction name"))
          return true;
      }
  
      switch (ParseInstruction(Inst, BB, PFS)) {
      default: llvm_unreachable("Unknown ParseInstruction result!");
      case InstError: return true;
      case InstNormal:
        BB->getInstList().push_back(Inst);
  
        // With a normal result, we check to see if the instruction is followed by
        // a comma and metadata.
        if (EatIfPresent(lltok::comma))
          if (ParseInstructionMetadata(Inst, &PFS))
            return true;
        break;
      case InstExtraComma:
        BB->getInstList().push_back(Inst);
  
        // If the instruction parser ate an extra comma at the end of it, it
        // *must* be followed by metadata.
        if (ParseInstructionMetadata(Inst, &PFS))
          return true;
        break;
      }
  
      // Set the name on the instruction.
      if (PFS.SetInstName(NameID, NameStr, NameLoc, Inst)) return true;
    } while (!isa<TerminatorInst>(Inst));
  
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Instruction Parsing.
  //===----------------------------------------------------------------------===//
  
  /// ParseInstruction - Parse one of the many different instructions.
  ///
  int LLParser::ParseInstruction(Instruction *&Inst, BasicBlock *BB,
                                 PerFunctionState &PFS) {
    lltok::Kind Token = Lex.getKind();
    if (Token == lltok::Eof)
      return TokError("found end of file when expecting more instructions");
    LocTy Loc = Lex.getLoc();
    unsigned KeywordVal = Lex.getUIntVal();
    Lex.Lex();  // Eat the keyword.
  
    switch (Token) {
    default:                    return Error(Loc, "expected instruction opcode");
    // Terminator Instructions.
    case lltok::kw_unreachable: Inst = new UnreachableInst(Context); return false;
    case lltok::kw_ret:         return ParseRet(Inst, BB, PFS);
    case lltok::kw_br:          return ParseBr(Inst, PFS);
    case lltok::kw_switch:      return ParseSwitch(Inst, PFS);
    case lltok::kw_indirectbr:  return ParseIndirectBr(Inst, PFS);
    case lltok::kw_invoke:      return ParseInvoke(Inst, PFS);
    case lltok::kw_resume:      return ParseResume(Inst, PFS);
    // Binary Operators.
    case lltok::kw_add:
    case lltok::kw_sub:
    case lltok::kw_mul:
    case lltok::kw_shl: {
      bool NUW = EatIfPresent(lltok::kw_nuw);
      bool NSW = EatIfPresent(lltok::kw_nsw);
      if (!NUW) NUW = EatIfPresent(lltok::kw_nuw);
  
      if (ParseArithmetic(Inst, PFS, KeywordVal, 1)) return true;
  
      if (NUW) cast<BinaryOperator>(Inst)->setHasNoUnsignedWrap(true);
      if (NSW) cast<BinaryOperator>(Inst)->setHasNoSignedWrap(true);
      return false;
    }
    case lltok::kw_fadd:
    case lltok::kw_fsub:
    case lltok::kw_fmul:
    case lltok::kw_fdiv:
    case lltok::kw_frem: {
      FastMathFlags FMF = EatFastMathFlagsIfPresent();
      int Res = ParseArithmetic(Inst, PFS, KeywordVal, 2);
      if (Res != 0)
        return Res;
      if (FMF.any())
        Inst->setFastMathFlags(FMF);
      return 0;
    }
  
    case lltok::kw_sdiv:
    case lltok::kw_udiv:
    case lltok::kw_lshr:
    case lltok::kw_ashr: {
      bool Exact = EatIfPresent(lltok::kw_exact);
  
      if (ParseArithmetic(Inst, PFS, KeywordVal, 1)) return true;
      if (Exact) cast<BinaryOperator>(Inst)->setIsExact(true);
      return false;
    }
  
    case lltok::kw_urem:
    case lltok::kw_srem:   return ParseArithmetic(Inst, PFS, KeywordVal, 1);
    case lltok::kw_and:
    case lltok::kw_or:
    case lltok::kw_xor:    return ParseLogical(Inst, PFS, KeywordVal);
    case lltok::kw_icmp:
    case lltok::kw_fcmp:   return ParseCompare(Inst, PFS, KeywordVal);
    // Casts.
    case lltok::kw_trunc:
    case lltok::kw_zext:
    case lltok::kw_sext:
    case lltok::kw_fptrunc:
    case lltok::kw_fpext:
    case lltok::kw_bitcast:
    case lltok::kw_addrspacecast:
    case lltok::kw_uitofp:
    case lltok::kw_sitofp:
    case lltok::kw_fptoui:
    case lltok::kw_fptosi:
    case lltok::kw_inttoptr:
    case lltok::kw_ptrtoint:       return ParseCast(Inst, PFS, KeywordVal);
    // Other.
    case lltok::kw_select:         return ParseSelect(Inst, PFS);
    case lltok::kw_va_arg:         return ParseVA_Arg(Inst, PFS);
    case lltok::kw_extractelement: return ParseExtractElement(Inst, PFS);
    case lltok::kw_insertelement:  return ParseInsertElement(Inst, PFS);
    case lltok::kw_shufflevector:  return ParseShuffleVector(Inst, PFS);
    case lltok::kw_phi:            return ParsePHI(Inst, PFS);
    case lltok::kw_landingpad:     return ParseLandingPad(Inst, PFS);
    // Call.
    case lltok::kw_call:     return ParseCall(Inst, PFS, CallInst::TCK_None);
    case lltok::kw_tail:     return ParseCall(Inst, PFS, CallInst::TCK_Tail);
    case lltok::kw_musttail: return ParseCall(Inst, PFS, CallInst::TCK_MustTail);
    // Memory.
    case lltok::kw_alloca:         return ParseAlloc(Inst, PFS);
    case lltok::kw_load:           return ParseLoad(Inst, PFS);
    case lltok::kw_store:          return ParseStore(Inst, PFS);
    case lltok::kw_cmpxchg:        return ParseCmpXchg(Inst, PFS);
    case lltok::kw_atomicrmw:      return ParseAtomicRMW(Inst, PFS);
    case lltok::kw_fence:          return ParseFence(Inst, PFS);
    case lltok::kw_getelementptr: return ParseGetElementPtr(Inst, PFS);
    case lltok::kw_extractvalue:  return ParseExtractValue(Inst, PFS);
    case lltok::kw_insertvalue:   return ParseInsertValue(Inst, PFS);
    }
  }
  
  /// ParseCmpPredicate - Parse an integer or fp predicate, based on Kind.
  bool LLParser::ParseCmpPredicate(unsigned &P, unsigned Opc) {
    if (Opc == Instruction::FCmp) {
      switch (Lex.getKind()) {
      default: return TokError("expected fcmp predicate (e.g. 'oeq')");
      case lltok::kw_oeq: P = CmpInst::FCMP_OEQ; break;
      case lltok::kw_one: P = CmpInst::FCMP_ONE; break;
      case lltok::kw_olt: P = CmpInst::FCMP_OLT; break;
      case lltok::kw_ogt: P = CmpInst::FCMP_OGT; break;
      case lltok::kw_ole: P = CmpInst::FCMP_OLE; break;
      case lltok::kw_oge: P = CmpInst::FCMP_OGE; break;
      case lltok::kw_ord: P = CmpInst::FCMP_ORD; break;
      case lltok::kw_uno: P = CmpInst::FCMP_UNO; break;
      case lltok::kw_ueq: P = CmpInst::FCMP_UEQ; break;
      case lltok::kw_une: P = CmpInst::FCMP_UNE; break;
      case lltok::kw_ult: P = CmpInst::FCMP_ULT; break;
      case lltok::kw_ugt: P = CmpInst::FCMP_UGT; break;
      case lltok::kw_ule: P = CmpInst::FCMP_ULE; break;
      case lltok::kw_uge: P = CmpInst::FCMP_UGE; break;
      case lltok::kw_true: P = CmpInst::FCMP_TRUE; break;
      case lltok::kw_false: P = CmpInst::FCMP_FALSE; break;
      }
    } else {
      switch (Lex.getKind()) {
      default: return TokError("expected icmp predicate (e.g. 'eq')");
      case lltok::kw_eq:  P = CmpInst::ICMP_EQ; break;
      case lltok::kw_ne:  P = CmpInst::ICMP_NE; break;
      case lltok::kw_slt: P = CmpInst::ICMP_SLT; break;
      case lltok::kw_sgt: P = CmpInst::ICMP_SGT; break;
      case lltok::kw_sle: P = CmpInst::ICMP_SLE; break;
      case lltok::kw_sge: P = CmpInst::ICMP_SGE; break;
      case lltok::kw_ult: P = CmpInst::ICMP_ULT; break;
      case lltok::kw_ugt: P = CmpInst::ICMP_UGT; break;
      case lltok::kw_ule: P = CmpInst::ICMP_ULE; break;
      case lltok::kw_uge: P = CmpInst::ICMP_UGE; break;
      }
    }
    Lex.Lex();
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Terminator Instructions.
  //===----------------------------------------------------------------------===//
  
  /// ParseRet - Parse a return instruction.
  ///   ::= 'ret' void (',' !dbg, !1)*
  ///   ::= 'ret' TypeAndValue (',' !dbg, !1)*
  bool LLParser::ParseRet(Instruction *&Inst, BasicBlock *BB,
                          PerFunctionState &PFS) {
    SMLoc TypeLoc = Lex.getLoc();
    Type *Ty = nullptr;
    if (ParseType(Ty, true /*void allowed*/)) return true;
  
    Type *ResType = PFS.getFunction().getReturnType();
  
    if (Ty->isVoidTy()) {
      if (!ResType->isVoidTy())
        return Error(TypeLoc, "value doesn't match function result type '" +
                     getTypeString(ResType) + "'");
  
      Inst = ReturnInst::Create(Context);
      return false;
    }
  
    Value *RV;
    if (ParseValue(Ty, RV, PFS)) return true;
  
    if (ResType != RV->getType())
      return Error(TypeLoc, "value doesn't match function result type '" +
                   getTypeString(ResType) + "'");
  
    Inst = ReturnInst::Create(Context, RV);
    return false;
  }
  
  
  /// ParseBr
  ///   ::= 'br' TypeAndValue
  ///   ::= 'br' TypeAndValue ',' TypeAndValue ',' TypeAndValue
  bool LLParser::ParseBr(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy Loc, Loc2;
    Value *Op0;
    BasicBlock *Op1, *Op2;
    if (ParseTypeAndValue(Op0, Loc, PFS)) return true;
  
    if (BasicBlock *BB = dyn_cast<BasicBlock>(Op0)) {
      Inst = BranchInst::Create(BB);
      return false;
    }
  
    if (Op0->getType() != Type::getInt1Ty(Context))
      return Error(Loc, "branch condition must have 'i1' type");
  
    if (ParseToken(lltok::comma, "expected ',' after branch condition") ||
        ParseTypeAndBasicBlock(Op1, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after true destination") ||
        ParseTypeAndBasicBlock(Op2, Loc2, PFS))
      return true;
  
    Inst = BranchInst::Create(Op1, Op2, Op0);
    return false;
  }
  
  /// ParseSwitch
  ///  Instruction
  ///    ::= 'switch' TypeAndValue ',' TypeAndValue '[' JumpTable ']'
  ///  JumpTable
  ///    ::= (TypeAndValue ',' TypeAndValue)*
  bool LLParser::ParseSwitch(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy CondLoc, BBLoc;
    Value *Cond;
    BasicBlock *DefaultBB;
    if (ParseTypeAndValue(Cond, CondLoc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after switch condition") ||
        ParseTypeAndBasicBlock(DefaultBB, BBLoc, PFS) ||
        ParseToken(lltok::lsquare, "expected '[' with switch table"))
      return true;
  
    if (!Cond->getType()->isIntegerTy())
      return Error(CondLoc, "switch condition must have integer type");
  
    // Parse the jump table pairs.
    SmallPtrSet<Value*, 32> SeenCases;
    SmallVector<std::pair<ConstantInt*, BasicBlock*>, 32> Table;
    while (Lex.getKind() != lltok::rsquare) {
      Value *Constant;
      BasicBlock *DestBB;
  
      if (ParseTypeAndValue(Constant, CondLoc, PFS) ||
          ParseToken(lltok::comma, "expected ',' after case value") ||
          ParseTypeAndBasicBlock(DestBB, PFS))
        return true;
  
      if (!SeenCases.insert(Constant).second)
        return Error(CondLoc, "duplicate case value in switch");
      if (!isa<ConstantInt>(Constant))
        return Error(CondLoc, "case value is not a constant integer");
  
      Table.push_back(std::make_pair(cast<ConstantInt>(Constant), DestBB));
    }
  
    Lex.Lex();  // Eat the ']'.
  
    SwitchInst *SI = SwitchInst::Create(Cond, DefaultBB, Table.size());
    for (unsigned i = 0, e = Table.size(); i != e; ++i)
      SI->addCase(Table[i].first, Table[i].second);
    Inst = SI;
    return false;
  }
  
  /// ParseIndirectBr
  ///  Instruction
  ///    ::= 'indirectbr' TypeAndValue ',' '[' LabelList ']'
  bool LLParser::ParseIndirectBr(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy AddrLoc;
    Value *Address;
    if (ParseTypeAndValue(Address, AddrLoc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after indirectbr address") ||
        ParseToken(lltok::lsquare, "expected '[' with indirectbr"))
      return true;
  
    if (!Address->getType()->isPointerTy())
      return Error(AddrLoc, "indirectbr address must have pointer type");
  
    // Parse the destination list.
    SmallVector<BasicBlock*, 16> DestList;
  
    if (Lex.getKind() != lltok::rsquare) {
      BasicBlock *DestBB;
      if (ParseTypeAndBasicBlock(DestBB, PFS))
        return true;
      DestList.push_back(DestBB);
  
      while (EatIfPresent(lltok::comma)) {
        if (ParseTypeAndBasicBlock(DestBB, PFS))
          return true;
        DestList.push_back(DestBB);
      }
    }
  
    if (ParseToken(lltok::rsquare, "expected ']' at end of block list"))
      return true;
  
    IndirectBrInst *IBI = IndirectBrInst::Create(Address, DestList.size());
    for (unsigned i = 0, e = DestList.size(); i != e; ++i)
      IBI->addDestination(DestList[i]);
    Inst = IBI;
    return false;
  }
  
  
  /// ParseInvoke
  ///   ::= 'invoke' OptionalCallingConv OptionalAttrs Type Value ParamList
  ///       OptionalAttrs 'to' TypeAndValue 'unwind' TypeAndValue
  bool LLParser::ParseInvoke(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy CallLoc = Lex.getLoc();
    AttrBuilder RetAttrs, FnAttrs;
    std::vector<unsigned> FwdRefAttrGrps;
    LocTy NoBuiltinLoc;
    unsigned CC;
    Type *RetType = nullptr;
    LocTy RetTypeLoc;
    ValID CalleeID;
    SmallVector<ParamInfo, 16> ArgList;
  
    BasicBlock *NormalBB, *UnwindBB;
    if (ParseOptionalCallingConv(CC) ||
        ParseOptionalReturnAttrs(RetAttrs) ||
        ParseType(RetType, RetTypeLoc, true /*void allowed*/) ||
        ParseValID(CalleeID) ||
        ParseParameterList(ArgList, PFS) ||
        ParseFnAttributeValuePairs(FnAttrs, FwdRefAttrGrps, false,
                                   NoBuiltinLoc) ||
        ParseToken(lltok::kw_to, "expected 'to' in invoke") ||
        ParseTypeAndBasicBlock(NormalBB, PFS) ||
        ParseToken(lltok::kw_unwind, "expected 'unwind' in invoke") ||
        ParseTypeAndBasicBlock(UnwindBB, PFS))
      return true;
  
    // If RetType is a non-function pointer type, then this is the short syntax
    // for the call, which means that RetType is just the return type.  Infer the
    // rest of the function argument types from the arguments that are present.
    PointerType *PFTy = nullptr;
    FunctionType *Ty = nullptr;
    if (!(PFTy = dyn_cast<PointerType>(RetType)) ||
        !(Ty = dyn_cast<FunctionType>(PFTy->getElementType()))) {
      // Pull out the types of all of the arguments...
      std::vector<Type*> ParamTypes;
      for (unsigned i = 0, e = ArgList.size(); i != e; ++i)
        ParamTypes.push_back(ArgList[i].V->getType());
  
      if (!FunctionType::isValidReturnType(RetType))
        return Error(RetTypeLoc, "Invalid result type for LLVM function");
  
      Ty = FunctionType::get(RetType, ParamTypes, false);
      PFTy = PointerType::getUnqual(Ty);
    }
  
    // Look up the callee.
    Value *Callee;
    if (ConvertValIDToValue(PFTy, CalleeID, Callee, &PFS)) return true;
  
    // Set up the Attribute for the function.
    SmallVector<AttributeSet, 8> Attrs;
    if (RetAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::ReturnIndex,
                                        RetAttrs));
  
    SmallVector<Value*, 8> Args;
  
    // Loop through FunctionType's arguments and ensure they are specified
    // correctly.  Also, gather any parameter attributes.
    FunctionType::param_iterator I = Ty->param_begin();
    FunctionType::param_iterator E = Ty->param_end();
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i) {
      Type *ExpectedTy = nullptr;
      if (I != E) {
        ExpectedTy = *I++;
      } else if (!Ty->isVarArg()) {
        return Error(ArgList[i].Loc, "too many arguments specified");
      }
  
      if (ExpectedTy && ExpectedTy != ArgList[i].V->getType())
        return Error(ArgList[i].Loc, "argument is not of expected type '" +
                     getTypeString(ExpectedTy) + "'");
      Args.push_back(ArgList[i].V);
      if (ArgList[i].Attrs.hasAttributes(i + 1)) {
        AttrBuilder B(ArgList[i].Attrs, i + 1);
        Attrs.push_back(AttributeSet::get(RetType->getContext(), i + 1, B));
      }
    }
  
    if (I != E)
      return Error(CallLoc, "not enough parameters specified for call");
  
    if (FnAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::FunctionIndex,
                                        FnAttrs));
  
    // Finish off the Attribute and check them
    AttributeSet PAL = AttributeSet::get(Context, Attrs);
  
    InvokeInst *II = InvokeInst::Create(Callee, NormalBB, UnwindBB, Args);
    II->setCallingConv(CC);
    II->setAttributes(PAL);
    ForwardRefAttrGroups[II] = FwdRefAttrGrps;
    Inst = II;
    return false;
  }
  
  /// ParseResume
  ///   ::= 'resume' TypeAndValue
  bool LLParser::ParseResume(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Exn; LocTy ExnLoc;
    if (ParseTypeAndValue(Exn, ExnLoc, PFS))
      return true;
  
    ResumeInst *RI = ResumeInst::Create(Exn);
    Inst = RI;
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Binary Operators.
  //===----------------------------------------------------------------------===//
  
  /// ParseArithmetic
  ///  ::= ArithmeticOps TypeAndValue ',' Value
  ///
  /// If OperandType is 0, then any FP or integer operand is allowed.  If it is 1,
  /// then any integer operand is allowed, if it is 2, any fp operand is allowed.
  bool LLParser::ParseArithmetic(Instruction *&Inst, PerFunctionState &PFS,
                                 unsigned Opc, unsigned OperandType) {
    LocTy Loc; Value *LHS, *RHS;
    if (ParseTypeAndValue(LHS, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' in arithmetic operation") ||
        ParseValue(LHS->getType(), RHS, PFS))
      return true;
  
    bool Valid;
    switch (OperandType) {
    default: llvm_unreachable("Unknown operand type!");
    case 0: // int or FP.
      Valid = LHS->getType()->isIntOrIntVectorTy() ||
              LHS->getType()->isFPOrFPVectorTy();
      break;
    case 1: Valid = LHS->getType()->isIntOrIntVectorTy(); break;
    case 2: Valid = LHS->getType()->isFPOrFPVectorTy(); break;
    }
  
    if (!Valid)
      return Error(Loc, "invalid operand type for instruction");
  
    Inst = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
    return false;
  }
  
  /// ParseLogical
  ///  ::= ArithmeticOps TypeAndValue ',' Value {
  bool LLParser::ParseLogical(Instruction *&Inst, PerFunctionState &PFS,
                              unsigned Opc) {
    LocTy Loc; Value *LHS, *RHS;
    if (ParseTypeAndValue(LHS, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' in logical operation") ||
        ParseValue(LHS->getType(), RHS, PFS))
      return true;
  
    if (!LHS->getType()->isIntOrIntVectorTy())
      return Error(Loc,"instruction requires integer or integer vector operands");
  
    Inst = BinaryOperator::Create((Instruction::BinaryOps)Opc, LHS, RHS);
    return false;
  }
  
  
  /// ParseCompare
  ///  ::= 'icmp' IPredicates TypeAndValue ',' Value
  ///  ::= 'fcmp' FPredicates TypeAndValue ',' Value
  bool LLParser::ParseCompare(Instruction *&Inst, PerFunctionState &PFS,
                              unsigned Opc) {
    // Parse the integer/fp comparison predicate.
    LocTy Loc;
    unsigned Pred;
    Value *LHS, *RHS;
    if (ParseCmpPredicate(Pred, Opc) ||
        ParseTypeAndValue(LHS, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after compare value") ||
        ParseValue(LHS->getType(), RHS, PFS))
      return true;
  
    if (Opc == Instruction::FCmp) {
      if (!LHS->getType()->isFPOrFPVectorTy())
        return Error(Loc, "fcmp requires floating point operands");
      Inst = new FCmpInst(CmpInst::Predicate(Pred), LHS, RHS);
    } else {
      assert(Opc == Instruction::ICmp && "Unknown opcode for CmpInst!");
      if (!LHS->getType()->isIntOrIntVectorTy() &&
          !LHS->getType()->getScalarType()->isPointerTy())
        return Error(Loc, "icmp requires integer operands");
      Inst = new ICmpInst(CmpInst::Predicate(Pred), LHS, RHS);
    }
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Other Instructions.
  //===----------------------------------------------------------------------===//
  
  
  /// ParseCast
  ///   ::= CastOpc TypeAndValue 'to' Type
  bool LLParser::ParseCast(Instruction *&Inst, PerFunctionState &PFS,
                           unsigned Opc) {
    LocTy Loc;
    Value *Op;
    Type *DestTy = nullptr;
    if (ParseTypeAndValue(Op, Loc, PFS) ||
        ParseToken(lltok::kw_to, "expected 'to' after cast value") ||
        ParseType(DestTy))
      return true;
  
    if (!CastInst::castIsValid((Instruction::CastOps)Opc, Op, DestTy)) {
      CastInst::castIsValid((Instruction::CastOps)Opc, Op, DestTy);
      return Error(Loc, "invalid cast opcode for cast from '" +
                   getTypeString(Op->getType()) + "' to '" +
                   getTypeString(DestTy) + "'");
    }
    Inst = CastInst::Create((Instruction::CastOps)Opc, Op, DestTy);
    return false;
  }
  
  /// ParseSelect
  ///   ::= 'select' TypeAndValue ',' TypeAndValue ',' TypeAndValue
  bool LLParser::ParseSelect(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy Loc;
    Value *Op0, *Op1, *Op2;
    if (ParseTypeAndValue(Op0, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after select condition") ||
        ParseTypeAndValue(Op1, PFS) ||
        ParseToken(lltok::comma, "expected ',' after select value") ||
        ParseTypeAndValue(Op2, PFS))
      return true;
  
    if (const char *Reason = SelectInst::areInvalidOperands(Op0, Op1, Op2))
      return Error(Loc, Reason);
  
    Inst = SelectInst::Create(Op0, Op1, Op2);
    return false;
  }
  
  /// ParseVA_Arg
  ///   ::= 'va_arg' TypeAndValue ',' Type
  bool LLParser::ParseVA_Arg(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Op;
    Type *EltTy = nullptr;
    LocTy TypeLoc;
    if (ParseTypeAndValue(Op, PFS) ||
        ParseToken(lltok::comma, "expected ',' after vaarg operand") ||
        ParseType(EltTy, TypeLoc))
      return true;
  
    if (!EltTy->isFirstClassType())
      return Error(TypeLoc, "va_arg requires operand with first class type");
  
    Inst = new VAArgInst(Op, EltTy);
    return false;
  }
  
  /// ParseExtractElement
  ///   ::= 'extractelement' TypeAndValue ',' TypeAndValue
  bool LLParser::ParseExtractElement(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy Loc;
    Value *Op0, *Op1;
    if (ParseTypeAndValue(Op0, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after extract value") ||
        ParseTypeAndValue(Op1, PFS))
      return true;
  
    if (!ExtractElementInst::isValidOperands(Op0, Op1))
      return Error(Loc, "invalid extractelement operands");
  
    Inst = ExtractElementInst::Create(Op0, Op1);
    return false;
  }
  
  /// ParseInsertElement
  ///   ::= 'insertelement' TypeAndValue ',' TypeAndValue ',' TypeAndValue
  bool LLParser::ParseInsertElement(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy Loc;
    Value *Op0, *Op1, *Op2;
    if (ParseTypeAndValue(Op0, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after insertelement value") ||
        ParseTypeAndValue(Op1, PFS) ||
        ParseToken(lltok::comma, "expected ',' after insertelement value") ||
        ParseTypeAndValue(Op2, PFS))
      return true;
  
    if (!InsertElementInst::isValidOperands(Op0, Op1, Op2))
      return Error(Loc, "invalid insertelement operands");
  
    Inst = InsertElementInst::Create(Op0, Op1, Op2);
    return false;
  }
  
  /// ParseShuffleVector
  ///   ::= 'shufflevector' TypeAndValue ',' TypeAndValue ',' TypeAndValue
  bool LLParser::ParseShuffleVector(Instruction *&Inst, PerFunctionState &PFS) {
    LocTy Loc;
    Value *Op0, *Op1, *Op2;
    if (ParseTypeAndValue(Op0, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after shuffle mask") ||
        ParseTypeAndValue(Op1, PFS) ||
        ParseToken(lltok::comma, "expected ',' after shuffle value") ||
        ParseTypeAndValue(Op2, PFS))
      return true;
  
    if (!ShuffleVectorInst::isValidOperands(Op0, Op1, Op2))
      return Error(Loc, "invalid shufflevector operands");
  
    Inst = new ShuffleVectorInst(Op0, Op1, Op2);
    return false;
  }
  
  /// ParsePHI
  ///   ::= 'phi' Type '[' Value ',' Value ']' (',' '[' Value ',' Value ']')*
  int LLParser::ParsePHI(Instruction *&Inst, PerFunctionState &PFS) {
    Type *Ty = nullptr;  LocTy TypeLoc;
    Value *Op0, *Op1;
  
    if (ParseType(Ty, TypeLoc) ||
        ParseToken(lltok::lsquare, "expected '[' in phi value list") ||
        ParseValue(Ty, Op0, PFS) ||
        ParseToken(lltok::comma, "expected ',' after insertelement value") ||
        ParseValue(Type::getLabelTy(Context), Op1, PFS) ||
        ParseToken(lltok::rsquare, "expected ']' in phi value list"))
      return true;
  
    bool AteExtraComma = false;
    SmallVector<std::pair<Value*, BasicBlock*>, 16> PHIVals;
    while (1) {
      PHIVals.push_back(std::make_pair(Op0, cast<BasicBlock>(Op1)));
  
      if (!EatIfPresent(lltok::comma))
        break;
  
      if (Lex.getKind() == lltok::MetadataVar) {
        AteExtraComma = true;
        break;
      }
  
      if (ParseToken(lltok::lsquare, "expected '[' in phi value list") ||
          ParseValue(Ty, Op0, PFS) ||
          ParseToken(lltok::comma, "expected ',' after insertelement value") ||
          ParseValue(Type::getLabelTy(Context), Op1, PFS) ||
          ParseToken(lltok::rsquare, "expected ']' in phi value list"))
        return true;
    }
  
    if (!Ty->isFirstClassType())
      return Error(TypeLoc, "phi node must have first class type");
  
    PHINode *PN = PHINode::Create(Ty, PHIVals.size());
    for (unsigned i = 0, e = PHIVals.size(); i != e; ++i)
      PN->addIncoming(PHIVals[i].first, PHIVals[i].second);
    Inst = PN;
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseLandingPad
  ///   ::= 'landingpad' Type 'personality' TypeAndValue 'cleanup'? Clause+
  /// Clause
  ///   ::= 'catch' TypeAndValue
  ///   ::= 'filter'
  ///   ::= 'filter' TypeAndValue ( ',' TypeAndValue )*
  bool LLParser::ParseLandingPad(Instruction *&Inst, PerFunctionState &PFS) {
    Type *Ty = nullptr; LocTy TyLoc;
    Value *PersFn; LocTy PersFnLoc;
  
    if (ParseType(Ty, TyLoc) ||
        ParseToken(lltok::kw_personality, "expected 'personality'") ||
        ParseTypeAndValue(PersFn, PersFnLoc, PFS))
      return true;
  
    LandingPadInst *LP = LandingPadInst::Create(Ty, PersFn, 0);
    LP->setCleanup(EatIfPresent(lltok::kw_cleanup));
  
    while (Lex.getKind() == lltok::kw_catch || Lex.getKind() == lltok::kw_filter){
      LandingPadInst::ClauseType CT;
      if (EatIfPresent(lltok::kw_catch))
        CT = LandingPadInst::Catch;
      else if (EatIfPresent(lltok::kw_filter))
        CT = LandingPadInst::Filter;
      else
        return TokError("expected 'catch' or 'filter' clause type");
  
      Value *V;
      LocTy VLoc;
      if (ParseTypeAndValue(V, VLoc, PFS)) {
        delete LP;
        return true;
      }
  
      // A 'catch' type expects a non-array constant. A filter clause expects an
      // array constant.
      if (CT == LandingPadInst::Catch) {
        if (isa<ArrayType>(V->getType()))
          Error(VLoc, "'catch' clause has an invalid type");
      } else {
        if (!isa<ArrayType>(V->getType()))
          Error(VLoc, "'filter' clause has an invalid type");
      }
  
      LP->addClause(cast<Constant>(V));
    }
  
    Inst = LP;
    return false;
  }
  
  /// ParseCall
  ///   ::= 'call' OptionalCallingConv OptionalAttrs Type Value
  ///       ParameterList OptionalAttrs
  ///   ::= 'tail' 'call' OptionalCallingConv OptionalAttrs Type Value
  ///       ParameterList OptionalAttrs
  ///   ::= 'musttail' 'call' OptionalCallingConv OptionalAttrs Type Value
  ///       ParameterList OptionalAttrs
  bool LLParser::ParseCall(Instruction *&Inst, PerFunctionState &PFS,
                           CallInst::TailCallKind TCK) {
    AttrBuilder RetAttrs, FnAttrs;
    std::vector<unsigned> FwdRefAttrGrps;
    LocTy BuiltinLoc;
    unsigned CC;
    Type *RetType = nullptr;
    LocTy RetTypeLoc;
    ValID CalleeID;
    SmallVector<ParamInfo, 16> ArgList;
    LocTy CallLoc = Lex.getLoc();
  
    if ((TCK != CallInst::TCK_None &&
         ParseToken(lltok::kw_call, "expected 'tail call'")) ||
        ParseOptionalCallingConv(CC) ||
        ParseOptionalReturnAttrs(RetAttrs) ||
        ParseType(RetType, RetTypeLoc, true /*void allowed*/) ||
        ParseValID(CalleeID) ||
        ParseParameterList(ArgList, PFS, TCK == CallInst::TCK_MustTail,
                           PFS.getFunction().isVarArg()) ||
        ParseFnAttributeValuePairs(FnAttrs, FwdRefAttrGrps, false,
                                   BuiltinLoc))
      return true;
  
    // If RetType is a non-function pointer type, then this is the short syntax
    // for the call, which means that RetType is just the return type.  Infer the
    // rest of the function argument types from the arguments that are present.
    PointerType *PFTy = nullptr;
    FunctionType *Ty = nullptr;
    if (!(PFTy = dyn_cast<PointerType>(RetType)) ||
        !(Ty = dyn_cast<FunctionType>(PFTy->getElementType()))) {
      // Pull out the types of all of the arguments...
      std::vector<Type*> ParamTypes;
      for (unsigned i = 0, e = ArgList.size(); i != e; ++i)
        ParamTypes.push_back(ArgList[i].V->getType());
  
      if (!FunctionType::isValidReturnType(RetType))
        return Error(RetTypeLoc, "Invalid result type for LLVM function");
  
      Ty = FunctionType::get(RetType, ParamTypes, false);
      PFTy = PointerType::getUnqual(Ty);
    }
  
    // Look up the callee.
    Value *Callee;
    if (ConvertValIDToValue(PFTy, CalleeID, Callee, &PFS)) return true;
  
    // Set up the Attribute for the function.
    SmallVector<AttributeSet, 8> Attrs;
    if (RetAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::ReturnIndex,
                                        RetAttrs));
  
    SmallVector<Value*, 8> Args;
  
    // Loop through FunctionType's arguments and ensure they are specified
    // correctly.  Also, gather any parameter attributes.
    FunctionType::param_iterator I = Ty->param_begin();
    FunctionType::param_iterator E = Ty->param_end();
    for (unsigned i = 0, e = ArgList.size(); i != e; ++i) {
      Type *ExpectedTy = nullptr;
      if (I != E) {
        ExpectedTy = *I++;
      } else if (!Ty->isVarArg()) {
        return Error(ArgList[i].Loc, "too many arguments specified");
      }
  
      if (ExpectedTy && ExpectedTy != ArgList[i].V->getType())
        return Error(ArgList[i].Loc, "argument is not of expected type '" +
                     getTypeString(ExpectedTy) + "'");
      Args.push_back(ArgList[i].V);
      if (ArgList[i].Attrs.hasAttributes(i + 1)) {
        AttrBuilder B(ArgList[i].Attrs, i + 1);
        Attrs.push_back(AttributeSet::get(RetType->getContext(), i + 1, B));
      }
    }
  
    if (I != E)
      return Error(CallLoc, "not enough parameters specified for call");
  
    if (FnAttrs.hasAttributes())
      Attrs.push_back(AttributeSet::get(RetType->getContext(),
                                        AttributeSet::FunctionIndex,
                                        FnAttrs));
  
    // Finish off the Attribute and check them
    AttributeSet PAL = AttributeSet::get(Context, Attrs);
  
    CallInst *CI = CallInst::Create(Callee, Args);
    CI->setTailCallKind(TCK);
    CI->setCallingConv(CC);
    CI->setAttributes(PAL);
    ForwardRefAttrGroups[CI] = FwdRefAttrGrps;
    Inst = CI;
    return false;
  }
  
  //===----------------------------------------------------------------------===//
  // Memory Instructions.
  //===----------------------------------------------------------------------===//
  
  /// ParseAlloc
  ///   ::= 'alloca' 'inalloca'? Type (',' TypeAndValue)? (',' 'align' i32)?
  int LLParser::ParseAlloc(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Size = nullptr;
    LocTy SizeLoc;
    unsigned Alignment = 0;
    Type *Ty = nullptr;
  
    bool IsInAlloca = EatIfPresent(lltok::kw_inalloca);
  
    if (ParseType(Ty)) return true;
  
    bool AteExtraComma = false;
    if (EatIfPresent(lltok::comma)) {
      if (Lex.getKind() == lltok::kw_align) {
        if (ParseOptionalAlignment(Alignment)) return true;
      } else if (Lex.getKind() == lltok::MetadataVar) {
        AteExtraComma = true;
      } else {
        if (ParseTypeAndValue(Size, SizeLoc, PFS) ||
            ParseOptionalCommaAlign(Alignment, AteExtraComma))
          return true;
      }
    }
  
    if (Size && !Size->getType()->isIntegerTy())
      return Error(SizeLoc, "element count must have integer type");
  
    AllocaInst *AI = new AllocaInst(Ty, Size, Alignment);
    AI->setUsedWithInAlloca(IsInAlloca);
    Inst = AI;
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseLoad
  ///   ::= 'load' 'volatile'? TypeAndValue (',' 'align' i32)?
  ///   ::= 'load' 'atomic' 'volatile'? TypeAndValue
  ///       'singlethread'? AtomicOrdering (',' 'align' i32)?
  int LLParser::ParseLoad(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Val; LocTy Loc;
    unsigned Alignment = 0;
    bool AteExtraComma = false;
    bool isAtomic = false;
    AtomicOrdering Ordering = NotAtomic;
    SynchronizationScope Scope = CrossThread;
  
    if (Lex.getKind() == lltok::kw_atomic) {
      isAtomic = true;
      Lex.Lex();
    }
  
    bool isVolatile = false;
    if (Lex.getKind() == lltok::kw_volatile) {
      isVolatile = true;
      Lex.Lex();
    }
  
    if (ParseTypeAndValue(Val, Loc, PFS) ||
        ParseScopeAndOrdering(isAtomic, Scope, Ordering) ||
        ParseOptionalCommaAlign(Alignment, AteExtraComma))
      return true;
  
    if (!Val->getType()->isPointerTy() ||
        !cast<PointerType>(Val->getType())->getElementType()->isFirstClassType())
      return Error(Loc, "load operand must be a pointer to a first class type");
    if (isAtomic && !Alignment)
      return Error(Loc, "atomic load must have explicit non-zero alignment");
    if (Ordering == Release || Ordering == AcquireRelease)
      return Error(Loc, "atomic load cannot use Release ordering");
  
    Inst = new LoadInst(Val, "", isVolatile, Alignment, Ordering, Scope);
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseStore
  
  ///   ::= 'store' 'volatile'? TypeAndValue ',' TypeAndValue (',' 'align' i32)?
  ///   ::= 'store' 'atomic' 'volatile'? TypeAndValue ',' TypeAndValue
  ///       'singlethread'? AtomicOrdering (',' 'align' i32)?
  int LLParser::ParseStore(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Val, *Ptr; LocTy Loc, PtrLoc;
    unsigned Alignment = 0;
    bool AteExtraComma = false;
    bool isAtomic = false;
    AtomicOrdering Ordering = NotAtomic;
    SynchronizationScope Scope = CrossThread;
  
    if (Lex.getKind() == lltok::kw_atomic) {
      isAtomic = true;
      Lex.Lex();
    }
  
    bool isVolatile = false;
    if (Lex.getKind() == lltok::kw_volatile) {
      isVolatile = true;
      Lex.Lex();
    }
  
    if (ParseTypeAndValue(Val, Loc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after store operand") ||
        ParseTypeAndValue(Ptr, PtrLoc, PFS) ||
        ParseScopeAndOrdering(isAtomic, Scope, Ordering) ||
        ParseOptionalCommaAlign(Alignment, AteExtraComma))
      return true;
  
    if (!Ptr->getType()->isPointerTy())
      return Error(PtrLoc, "store operand must be a pointer");
    if (!Val->getType()->isFirstClassType())
      return Error(Loc, "store operand must be a first class value");
    if (cast<PointerType>(Ptr->getType())->getElementType() != Val->getType())
      return Error(Loc, "stored value and pointer type do not match");
    if (isAtomic && !Alignment)
      return Error(Loc, "atomic store must have explicit non-zero alignment");
    if (Ordering == Acquire || Ordering == AcquireRelease)
      return Error(Loc, "atomic store cannot use Acquire ordering");
  
    Inst = new StoreInst(Val, Ptr, isVolatile, Alignment, Ordering, Scope);
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseCmpXchg
  ///   ::= 'cmpxchg' 'weak'? 'volatile'? TypeAndValue ',' TypeAndValue ','
  ///       TypeAndValue 'singlethread'? AtomicOrdering AtomicOrdering
  int LLParser::ParseCmpXchg(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Ptr, *Cmp, *New; LocTy PtrLoc, CmpLoc, NewLoc;
    bool AteExtraComma = false;
    AtomicOrdering SuccessOrdering = NotAtomic;
    AtomicOrdering FailureOrdering = NotAtomic;
    SynchronizationScope Scope = CrossThread;
    bool isVolatile = false;
    bool isWeak = false;
  
    if (EatIfPresent(lltok::kw_weak))
      isWeak = true;
  
    if (EatIfPresent(lltok::kw_volatile))
      isVolatile = true;
  
    if (ParseTypeAndValue(Ptr, PtrLoc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after cmpxchg address") ||
        ParseTypeAndValue(Cmp, CmpLoc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after cmpxchg cmp operand") ||
        ParseTypeAndValue(New, NewLoc, PFS) ||
        ParseScopeAndOrdering(true /*Always atomic*/, Scope, SuccessOrdering) ||
        ParseOrdering(FailureOrdering))
      return true;
  
    if (SuccessOrdering == Unordered || FailureOrdering == Unordered)
      return TokError("cmpxchg cannot be unordered");
    if (SuccessOrdering < FailureOrdering)
      return TokError("cmpxchg must be at least as ordered on success as failure");
    if (FailureOrdering == Release || FailureOrdering == AcquireRelease)
      return TokError("cmpxchg failure ordering cannot include release semantics");
    if (!Ptr->getType()->isPointerTy())
      return Error(PtrLoc, "cmpxchg operand must be a pointer");
    if (cast<PointerType>(Ptr->getType())->getElementType() != Cmp->getType())
      return Error(CmpLoc, "compare value and pointer type do not match");
    if (cast<PointerType>(Ptr->getType())->getElementType() != New->getType())
      return Error(NewLoc, "new value and pointer type do not match");
    if (!New->getType()->isIntegerTy())
      return Error(NewLoc, "cmpxchg operand must be an integer");
    unsigned Size = New->getType()->getPrimitiveSizeInBits();
    if (Size < 8 || (Size & (Size - 1)))
      return Error(NewLoc, "cmpxchg operand must be power-of-two byte-sized"
                           " integer");
  
    AtomicCmpXchgInst *CXI = new AtomicCmpXchgInst(
        Ptr, Cmp, New, SuccessOrdering, FailureOrdering, Scope);
    CXI->setVolatile(isVolatile);
    CXI->setWeak(isWeak);
    Inst = CXI;
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseAtomicRMW
  ///   ::= 'atomicrmw' 'volatile'? BinOp TypeAndValue ',' TypeAndValue
  ///       'singlethread'? AtomicOrdering
  int LLParser::ParseAtomicRMW(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Ptr, *Val; LocTy PtrLoc, ValLoc;
    bool AteExtraComma = false;
    AtomicOrdering Ordering = NotAtomic;
    SynchronizationScope Scope = CrossThread;
    bool isVolatile = false;
    AtomicRMWInst::BinOp Operation;
  
    if (EatIfPresent(lltok::kw_volatile))
      isVolatile = true;
  
    switch (Lex.getKind()) {
    default: return TokError("expected binary operation in atomicrmw");
    case lltok::kw_xchg: Operation = AtomicRMWInst::Xchg; break;
    case lltok::kw_add: Operation = AtomicRMWInst::Add; break;
    case lltok::kw_sub: Operation = AtomicRMWInst::Sub; break;
    case lltok::kw_and: Operation = AtomicRMWInst::And; break;
    case lltok::kw_nand: Operation = AtomicRMWInst::Nand; break;
    case lltok::kw_or: Operation = AtomicRMWInst::Or; break;
    case lltok::kw_xor: Operation = AtomicRMWInst::Xor; break;
    case lltok::kw_max: Operation = AtomicRMWInst::Max; break;
    case lltok::kw_min: Operation = AtomicRMWInst::Min; break;
    case lltok::kw_umax: Operation = AtomicRMWInst::UMax; break;
    case lltok::kw_umin: Operation = AtomicRMWInst::UMin; break;
    }
    Lex.Lex();  // Eat the operation.
  
    if (ParseTypeAndValue(Ptr, PtrLoc, PFS) ||
        ParseToken(lltok::comma, "expected ',' after atomicrmw address") ||
        ParseTypeAndValue(Val, ValLoc, PFS) ||
        ParseScopeAndOrdering(true /*Always atomic*/, Scope, Ordering))
      return true;
  
    if (Ordering == Unordered)
      return TokError("atomicrmw cannot be unordered");
    if (!Ptr->getType()->isPointerTy())
      return Error(PtrLoc, "atomicrmw operand must be a pointer");
    if (cast<PointerType>(Ptr->getType())->getElementType() != Val->getType())
      return Error(ValLoc, "atomicrmw value and pointer type do not match");
    if (!Val->getType()->isIntegerTy())
      return Error(ValLoc, "atomicrmw operand must be an integer");
    unsigned Size = Val->getType()->getPrimitiveSizeInBits();
    if (Size < 8 || (Size & (Size - 1)))
      return Error(ValLoc, "atomicrmw operand must be power-of-two byte-sized"
                           " integer");
  
    AtomicRMWInst *RMWI =
      new AtomicRMWInst(Operation, Ptr, Val, Ordering, Scope);
    RMWI->setVolatile(isVolatile);
    Inst = RMWI;
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseFence
  ///   ::= 'fence' 'singlethread'? AtomicOrdering
  int LLParser::ParseFence(Instruction *&Inst, PerFunctionState &PFS) {
    AtomicOrdering Ordering = NotAtomic;
    SynchronizationScope Scope = CrossThread;
    if (ParseScopeAndOrdering(true /*Always atomic*/, Scope, Ordering))
      return true;
  
    if (Ordering == Unordered)
      return TokError("fence cannot be unordered");
    if (Ordering == Monotonic)
      return TokError("fence cannot be monotonic");
  
    Inst = new FenceInst(Context, Ordering, Scope);
    return InstNormal;
  }
  
  /// ParseGetElementPtr
  ///   ::= 'getelementptr' 'inbounds'? TypeAndValue (',' TypeAndValue)*
  int LLParser::ParseGetElementPtr(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Ptr = nullptr;
    Value *Val = nullptr;
    LocTy Loc, EltLoc;
  
    bool InBounds = EatIfPresent(lltok::kw_inbounds);
  
    if (ParseTypeAndValue(Ptr, Loc, PFS)) return true;
  
    Type *BaseType = Ptr->getType();
    PointerType *BasePointerType = dyn_cast<PointerType>(BaseType->getScalarType());
    if (!BasePointerType)
      return Error(Loc, "base of getelementptr must be a pointer");
  
    SmallVector<Value*, 16> Indices;
    bool AteExtraComma = false;
    while (EatIfPresent(lltok::comma)) {
      if (Lex.getKind() == lltok::MetadataVar) {
        AteExtraComma = true;
        break;
      }
      if (ParseTypeAndValue(Val, EltLoc, PFS)) return true;
      if (!Val->getType()->getScalarType()->isIntegerTy())
        return Error(EltLoc, "getelementptr index must be an integer");
      if (Val->getType()->isVectorTy() != Ptr->getType()->isVectorTy())
        return Error(EltLoc, "getelementptr index type missmatch");
      if (Val->getType()->isVectorTy()) {
        unsigned ValNumEl = cast<VectorType>(Val->getType())->getNumElements();
        unsigned PtrNumEl = cast<VectorType>(Ptr->getType())->getNumElements();
        if (ValNumEl != PtrNumEl)
          return Error(EltLoc,
            "getelementptr vector index has a wrong number of elements");
      }
      Indices.push_back(Val);
    }
  
    if (!Indices.empty() && !BasePointerType->getElementType()->isSized())
      return Error(Loc, "base element of getelementptr must be sized");
  
    if (!GetElementPtrInst::getIndexedType(BaseType, Indices))
      return Error(Loc, "invalid getelementptr indices");
    Inst = GetElementPtrInst::Create(Ptr, Indices);
    if (InBounds)
      cast<GetElementPtrInst>(Inst)->setIsInBounds(true);
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseExtractValue
  ///   ::= 'extractvalue' TypeAndValue (',' uint32)+
  int LLParser::ParseExtractValue(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Val; LocTy Loc;
    SmallVector<unsigned, 4> Indices;
    bool AteExtraComma;
    if (ParseTypeAndValue(Val, Loc, PFS) ||
        ParseIndexList(Indices, AteExtraComma))
      return true;
  
    if (!Val->getType()->isAggregateType())
      return Error(Loc, "extractvalue operand must be aggregate type");
  
    if (!ExtractValueInst::getIndexedType(Val->getType(), Indices))
      return Error(Loc, "invalid indices for extractvalue");
    Inst = ExtractValueInst::Create(Val, Indices);
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  /// ParseInsertValue
  ///   ::= 'insertvalue' TypeAndValue ',' TypeAndValue (',' uint32)+
  int LLParser::ParseInsertValue(Instruction *&Inst, PerFunctionState &PFS) {
    Value *Val0, *Val1; LocTy Loc0, Loc1;
    SmallVector<unsigned, 4> Indices;
    bool AteExtraComma;
    if (ParseTypeAndValue(Val0, Loc0, PFS) ||
        ParseToken(lltok::comma, "expected comma after insertvalue operand") ||
        ParseTypeAndValue(Val1, Loc1, PFS) ||
        ParseIndexList(Indices, AteExtraComma))
      return true;
  
    if (!Val0->getType()->isAggregateType())
      return Error(Loc0, "insertvalue operand must be aggregate type");
  
    if (!ExtractValueInst::getIndexedType(Val0->getType(), Indices))
      return Error(Loc0, "invalid indices for insertvalue");
    Inst = InsertValueInst::Create(Val0, Val1, Indices);
    return AteExtraComma ? InstExtraComma : InstNormal;
  }
  
  //===----------------------------------------------------------------------===//
  // Embedded metadata.
  //===----------------------------------------------------------------------===//
  
  /// ParseMDNodeVector
  ///   ::= { Element (',' Element)* }
  /// Element
  ///   ::= 'null' | TypeAndValue
  bool LLParser::ParseMDNodeVector(SmallVectorImpl<Metadata *> &Elts) {
    if (ParseToken(lltok::lbrace, "expected '{' here"))
      return true;
  
    // Check for an empty list.
    if (EatIfPresent(lltok::rbrace))
      return false;
  
    do {
      // Null is a special case since it is typeless.
      if (EatIfPresent(lltok::kw_null)) {
        Elts.push_back(nullptr);
        continue;
      }
  
      Metadata *MD;
      if (ParseMetadata(MD, nullptr))
        return true;
      Elts.push_back(MD);
    } while (EatIfPresent(lltok::comma));
  
    return ParseToken(lltok::rbrace, "expected end of metadata node");
  }
  
  //===----------------------------------------------------------------------===//
  // Use-list order directives.
  //===----------------------------------------------------------------------===//
  bool LLParser::sortUseListOrder(Value *V, ArrayRef<unsigned> Indexes,
                                  SMLoc Loc) {
    if (V->use_empty())
      return Error(Loc, "value has no uses");
  
    unsigned NumUses = 0;
    SmallDenseMap<const Use *, unsigned, 16> Order;
    for (const Use &U : V->uses()) {
      if (++NumUses > Indexes.size())
        break;
      Order[&U] = Indexes[NumUses - 1];
    }
    if (NumUses < 2)
      return Error(Loc, "value only has one use");
    if (Order.size() != Indexes.size() || NumUses > Indexes.size())
      return Error(Loc, "wrong number of indexes, expected " +
                            Twine(std::distance(V->use_begin(), V->use_end())));
  
    V->sortUseList([&](const Use &L, const Use &R) {
      return Order.lookup(&L) < Order.lookup(&R);
    });
    return false;
  }
  
  /// ParseUseListOrderIndexes
  ///   ::= '{' uint32 (',' uint32)+ '}'
  bool LLParser::ParseUseListOrderIndexes(SmallVectorImpl<unsigned> &Indexes) {
    SMLoc Loc = Lex.getLoc();
    if (ParseToken(lltok::lbrace, "expected '{' here"))
      return true;
    if (Lex.getKind() == lltok::rbrace)
      return Lex.Error("expected non-empty list of uselistorder indexes");
  
    // Use Offset, Max, and IsOrdered to check consistency of indexes.  The
    // indexes should be distinct numbers in the range [0, size-1], and should
    // not be in order.
    unsigned Offset = 0;
    unsigned Max = 0;
    bool IsOrdered = true;
    assert(Indexes.empty() && "Expected empty order vector");
    do {
      unsigned Index;
      if (ParseUInt32(Index))
        return true;
  
      // Update consistency checks.
      Offset += Index - Indexes.size();
      Max = std::max(Max, Index);
      IsOrdered &= Index == Indexes.size();
  
      Indexes.push_back(Index);
    } while (EatIfPresent(lltok::comma));
  
    if (ParseToken(lltok::rbrace, "expected '}' here"))
      return true;
  
    if (Indexes.size() < 2)
      return Error(Loc, "expected >= 2 uselistorder indexes");
    if (Offset != 0 || Max >= Indexes.size())
      return Error(Loc, "expected distinct uselistorder indexes in range [0, size)");
    if (IsOrdered)
      return Error(Loc, "expected uselistorder indexes to change the order");
  
    return false;
  }
  
  /// ParseUseListOrder
  ///   ::= 'uselistorder' Type Value ',' UseListOrderIndexes
  bool LLParser::ParseUseListOrder(PerFunctionState *PFS) {
    SMLoc Loc = Lex.getLoc();
    if (ParseToken(lltok::kw_uselistorder, "expected uselistorder directive"))
      return true;
  
    Value *V;
    SmallVector<unsigned, 16> Indexes;
    if (ParseTypeAndValue(V, PFS) ||
        ParseToken(lltok::comma, "expected comma in uselistorder directive") ||
        ParseUseListOrderIndexes(Indexes))
      return true;
  
    return sortUseListOrder(V, Indexes, Loc);
  }
  
  /// ParseUseListOrderBB
  ///   ::= 'uselistorder_bb' @foo ',' %bar ',' UseListOrderIndexes
  bool LLParser::ParseUseListOrderBB() {
    assert(Lex.getKind() == lltok::kw_uselistorder_bb);
    SMLoc Loc = Lex.getLoc();
    Lex.Lex();
  
    ValID Fn, Label;
    SmallVector<unsigned, 16> Indexes;
    if (ParseValID(Fn) ||
        ParseToken(lltok::comma, "expected comma in uselistorder_bb directive") ||
        ParseValID(Label) ||
        ParseToken(lltok::comma, "expected comma in uselistorder_bb directive") ||
        ParseUseListOrderIndexes(Indexes))
      return true;
  
    // Check the function.
    GlobalValue *GV;
    if (Fn.Kind == ValID::t_GlobalName)
      GV = M->getNamedValue(Fn.StrVal);
    else if (Fn.Kind == ValID::t_GlobalID)
      GV = Fn.UIntVal < NumberedVals.size() ? NumberedVals[Fn.UIntVal] : nullptr;
    else
      return Error(Fn.Loc, "expected function name in uselistorder_bb");
    if (!GV)
      return Error(Fn.Loc, "invalid function forward reference in uselistorder_bb");
    auto *F = dyn_cast<Function>(GV);
    if (!F)
      return Error(Fn.Loc, "expected function name in uselistorder_bb");
    if (F->isDeclaration())
      return Error(Fn.Loc, "invalid declaration in uselistorder_bb");
  
    // Check the basic block.
    if (Label.Kind == ValID::t_LocalID)
      return Error(Label.Loc, "invalid numeric label in uselistorder_bb");
    if (Label.Kind != ValID::t_LocalName)
      return Error(Label.Loc, "expected basic block name in uselistorder_bb");
    Value *V = F->getValueSymbolTable().lookup(Label.StrVal);
    if (!V)
      return Error(Label.Loc, "invalid basic block in uselistorder_bb");
    if (!isa<BasicBlock>(V))
      return Error(Label.Loc, "expected basic block in uselistorder_bb");
  
    return sortUseListOrder(V, Indexes, Loc);
  }
  