[Coverity] Fix uninitialized scalar members

[akshaykhadse]

Summary

This change fixes static code analysis errors

[LuoYuanke]

LGTM.

llvm/include/llvm/InterfaceStub/IFSStub.h

enum class IFSBitWidthType {
   Unknown = 256,
 };
 
 struct IFSSymbol {
   IFSSymbol() = default;
   explicit IFSSymbol(std::string SymbolName) : Name(std::move(SymbolName)) {}
   std::string Name;
   std::optional<uint64_t> Size;
-  IFSSymbolType Type;
-  bool Undefined;
-  bool Weak;
+  IFSSymbolType Type = IFSSymbolType::NoType;
+  bool Undefined = false;
+  bool Weak = false;
   std::optional<std::string> Warning;
   bool operator<(const IFSSymbol &RHS) const { return Name < RHS.Name; }
 };
 
 struct IFSTarget {
   std::optional<std::string> Triple;
   std::optional<std::string> ObjectFormat;
   std::optional<IFSArch> Arch;

llvm/include/llvm/Object/ELFObjectFile.h

for (const Elf_Shdr &Sec : *SectionsOrErr) {
       }
     }
     return Error::success();
   }
 
   // This flag is used for classof, to distinguish ELFObjectFile from
   // its subclass. If more subclasses will be created, this flag will
   // have to become an enum.
-  bool isDyldELFObject;
+  bool isDyldELFObject = false;
 
 public:
   ELFObjectFile(ELFObjectFile<ELFT> &&Other);
   static Expected<ELFObjectFile<ELFT>> create(MemoryBufferRef Object,
                                               bool InitContent = true);
 
   const Elf_Rel *getRel(DataRefImpl Rel) const;
   const Elf_Rela *getRela(DataRefImpl Rela) const;

llvm/include/llvm/Object/WindowsResource.h

private:
     // The .res file that defined this TreeNode, for diagnostics.
     // Index into InputFilenames.
     uint32_t Origin;
   };
 
   struct StringOrID {
     bool IsString;
     ArrayRef<UTF16> String;
-    uint32_t ID;
+    uint32_t ID = ~0u;
 
     StringOrID(uint32_t ID) : IsString(false), ID(ID) {}
     StringOrID(ArrayRef<UTF16> String) : IsString(true), String(String) {}
   };
 
 private:
   Error addChildren(TreeNode &Node, ResourceSectionRef &RSR,
                     const coff_resource_dir_table &Table, uint32_t Origin,

llvm/lib/ObjectYAML/XCOFFEmitter.cpp

private:
   void writeAuxSymbol(const XCOFFYAML::SectAuxEntForStat &AuxSym);
   void writeAuxSymbol(const std::unique_ptr<XCOFFYAML::AuxSymbolEnt> &AuxSym);
 
   XCOFFYAML::Object &Obj;
   bool Is64Bit = false;
   support::endian::Writer W;
   yaml::ErrorHandler ErrHandler;
   StringTableBuilder StrTblBuilder;
-  uint64_t StartOffset;
+  uint64_t StartOffset = 0u;
   // Map the section name to its corrresponding section index.
   DenseMap<StringRef, int16_t> SectionIndexMap = {
       {StringRef("N_DEBUG"), XCOFF::N_DEBUG},
       {StringRef("N_ABS"), XCOFF::N_ABS},
       {StringRef("N_UNDEF"), XCOFF::N_UNDEF}};
   XCOFFYAML::FileHeader InitFileHdr = Obj.Header;
   XCOFFYAML::AuxiliaryHeader InitAuxFileHdr;
   std::vector<XCOFFYAML::Section> InitSections = Obj.Sections;

llvm/lib/Target/X86/MCTargetDesc/X86AsmBackend.cpp

class X86AsmBackend : public MCAsmBackend {
   std::unique_ptr<const MCInstrInfo> MCII;
   X86AlignBranchKind AlignBranchType;
   Align AlignBoundary;
   unsigned TargetPrefixMax = 0;
 
   MCInst PrevInst;
   MCBoundaryAlignFragment *PendingBA = nullptr;
   std::pair<MCFragment *, size_t> PrevInstPosition;
-  bool CanPadInst;
+  bool CanPadInst = false;
 
   uint8_t determinePaddingPrefix(const MCInst &Inst) const;
   bool isMacroFused(const MCInst &Cmp, const MCInst &Jcc) const;
   bool needAlign(const MCInst &Inst) const;
   bool canPadBranches(MCObjectStreamer &OS) const;
   bool canPadInst(const MCInst &Inst, MCObjectStreamer &OS) const;
 
 public: