C++ Twine类代码示例

void native(const Twine &path, SmallVectorImpl<char> &result, Style style) {
  assert((!path.isSingleStringRef() ||
          path.getSingleStringRef().data() != result.data()) &&
         "path and result are not allowed to overlap!");
  // Clear result.
  result.clear();
  path.toVector(result);
  native(result, style);
}

void Value::setName(const Twine &NewName) {
  assert(SubclassID != MDStringVal &&
         "Cannot set the name of MDString with this method!");

  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  StringRef NameRef = NewName.toStringRef(NameData);

  // Name isn't changing?
  if (getName() == NameRef)
    return;

  assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameRef.empty()) {
      // Free the name for this value.
      Name->Destroy();
      Name = 0;
      return;
    }

    if (Name)
      Name->Destroy();

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.

    // Create the new name.
    Name = ValueName::Create(NameRef.begin(), NameRef.end());
    Name->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(Name);
    Name->Destroy();
    Name = 0;

    if (NameRef.empty())
      return;
  }

  // Name is changing to something new.
  Name = ST->createValueName(NameRef, this);
}

/// \brief Construct a triple from string representations of the architecture,
/// vendor, and OS.
///
/// This joins each argument into a canonical string representation and parses
/// them into enum members. It leaves the environment unknown and omits it from
/// the string representation.
Triple::Triple(const Twine &ArchStr, const Twine &VendorStr, const Twine &OSStr)
    : Data((ArchStr + Twine('-') + VendorStr + Twine('-') + OSStr).str()),
      Arch(parseArch(ArchStr.str())),
      SubArch(parseSubArch(ArchStr.str())),
      Vendor(parseVendor(VendorStr.str())),
      OS(parseOS(OSStr.str())),
      Environment(), ObjectFormat(Triple::UnknownObjectFormat) {
  ObjectFormat = getDefaultFormat(*this);
}

void Attributes::addComment(const Twine &Comment) {
  if (!Comment.isTriviallyEmpty()) {
    if (Comments.empty())
      Comments = " // ";
    else
      Comments += ", ";
    Comments += Comment.str();
  }
}

/// \brief Construct a triple from string representations of the architecture,
/// vendor, OS, and environment.
///
/// This joins each argument into a canonical string representation and parses
/// them into enum members.
Triple::Triple(const Twine &ArchStr, const Twine &VendorStr, const Twine &OSStr,
               const Twine &EnvironmentStr)
    : Data((ArchStr + Twine('-') + VendorStr + Twine('-') + OSStr + Twine('-') +
            EnvironmentStr).str()),
      Arch(parseArch(ArchStr.str())),
      Vendor(parseVendor(VendorStr.str())),
      OS(parseOS(OSStr.str())),
      Environment(parseEnvironment(EnvironmentStr.str())) {
}

void Attributes::add(const Twine &Name, const Twine &Value,
                     const Twine &Comment) {
  std::string A = Name.str();
  A += "=\"";
  A += Value.str();
  A += "\"";
  Attrs.push_back(A);
  addComment(Comment);
}

void Value::setNameImpl(const Twine &NewName) {
  // Fast-path: LLVMContext can be set to strip out non-GlobalValue names
  if (getContext().shouldDiscardValueNames() && !isa<GlobalValue>(this))
    return;

  // Fast path for common IRBuilder case of setName("") when there is no name.
  if (NewName.isTriviallyEmpty() && !hasName())
    return;

  SmallString<256> NameData;
  StringRef NameRef = NewName.toStringRef(NameData);
  assert(NameRef.find_first_of(0) == StringRef::npos &&
         "Null bytes are not allowed in names");

  // Name isn't changing?
  if (getName() == NameRef)
    return;

  assert(!getType()->isVoidTy() && "Cannot assign a name to void values!");

  // Get the symbol table to update for this object.
  ValueSymbolTable *ST;
  if (getSymTab(this, ST))
    return;  // Cannot set a name on this value (e.g. constant).

  if (!ST) { // No symbol table to update?  Just do the change.
    if (NameRef.empty()) {
      // Free the name for this value.
      destroyValueName();
      return;
    }

    // NOTE: Could optimize for the case the name is shrinking to not deallocate
    // then reallocated.
    destroyValueName();

    // Create the new name.
    setValueName(ValueName::Create(NameRef));
    getValueName()->setValue(this);
    return;
  }

  // NOTE: Could optimize for the case the name is shrinking to not deallocate
  // then reallocated.
  if (hasName()) {
    // Remove old name.
    ST->removeValueName(getValueName());
    destroyValueName();

    if (NameRef.empty())
      return;
  }

  // Name is changing to something new.
  setValueName(ST->createValueName(NameRef, this));
}

void Attributes::add(const Twine &Name, const Twine &Value,
                     const Twine &Comment) {
  std::string A = Name.str();
  A += "=\"";
  A += Value.str();
  A += "\"";
  Attrs.push_back(A);
  if (!Comment.isTriviallyEmpty()) {
    if (Comments.empty())
      Comments = " // ";
    else
      Comments += ", ";
    Comments += Comment.str();
  }
}

bool runToolOnCodeWithArgs(clang::FrontendAction *ToolAction, const Twine &Code,
                           const std::vector<std::string> &Args,
                           const Twine &FileName) {
  SmallString<16> FileNameStorage;
  StringRef FileNameRef = FileName.toNullTerminatedStringRef(FileNameStorage);
  llvm::IntrusiveRefCntPtr<FileManager> Files(
      new FileManager(FileSystemOptions()));
  ToolInvocation Invocation(getSyntaxOnlyToolArgs(Args, FileNameRef), ToolAction,
                            Files.getPtr());

  SmallString<1024> CodeStorage;
  Invocation.mapVirtualFile(FileNameRef,
                            Code.toNullTerminatedStringRef(CodeStorage));
  return Invocation.run();
}

bool FileRemapper::report(const Twine &err, DiagnosticsEngine &Diag) {
  SmallString<128> buf;
  unsigned ID = Diag.getDiagnosticIDs()->getCustomDiagID(DiagnosticIDs::Error,
                                                         err.toStringRef(buf));
  Diag.Report(ID);
  return true;
}

// This is for use when debugging LTO.
static void saveBuffer(StringRef Buffer, const Twine &Path) {
  std::error_code EC;
  raw_fd_ostream OS(Path.str(), EC, sys::fs::OpenFlags::F_None);
  if (EC)
    error(EC, "cannot create " + Path);
  OS << Buffer;
}

static std::string GetName(Value *V) {
  static unsigned Id = 0;
  if (!Ids.count(V))
    Ids[V] = Id++;

  Twine Name;
  if (V->hasName()) {
    if (isa<Instruction>(V) || isa<Argument>(V))
      Name = V->getName();
    else
      Name = "__SRA_SYM_UNKNOWN_" + V->getName() + "__";
  } else {
    Name = "__SRA_SYM_UNAMED__";
  }
  return Name.str() + "." + std::to_string(Ids[V]);
}

/// getNameWithPrefix - Fill OutName with the name of the appropriate prefix
/// and the specified name as the global variable name.  GVName must not be
/// empty.
void Mangler::getNameWithPrefix(SmallVectorImpl<char> &OutName,
                                const Twine &GVName, ManglerPrefixTy PrefixTy) {
  SmallString<256> TmpData;
  StringRef Name = GVName.toStringRef(TmpData);
  assert(!Name.empty() && "getNameWithPrefix requires non-empty name");

  // If the global name is not led with \1, add the appropriate prefixes.
  if (Name[0] == '\1') {
    Name = Name.substr(1);
  } else {
    if (PrefixTy == Mangler::Private) {
      const char *Prefix = DL->getPrivateGlobalPrefix();
      OutName.append(Prefix, Prefix+strlen(Prefix));
    } else if (PrefixTy == Mangler::LinkerPrivate) {
      const char *Prefix = DL->getLinkerPrivateGlobalPrefix();
      OutName.append(Prefix, Prefix+strlen(Prefix));
    }

    char Prefix = DL->getGlobalPrefix();
    if (Prefix != '\0')
      OutName.push_back(Prefix);
  }

  // If this is a simple string that doesn't need escaping, just append it.
  OutName.append(Name.begin(), Name.end());
}

static bool dumpObjectFile(ObjectFile &Obj, DWARFContext &DICtx, Twine Filename,
                           raw_ostream &OS) {
  logAllUnhandledErrors(DICtx.loadRegisterInfo(Obj), errs(),
                        Filename.str() + ": ");
  // The UUID dump already contains all the same information.
  if (!(DumpType & DIDT_UUID) || DumpType == DIDT_All)
    OS << Filename << ":\tfile format " << Obj.getFileFormatName() << '\n';

  // Handle the --lookup option.
  if (Lookup)
    return lookup(DICtx, Lookup, OS);

  // Handle the --name option.
  if (!Name.empty()) {
    StringSet<> Names;
    for (auto name : Name)
      Names.insert((IgnoreCase && !UseRegex) ? StringRef(name).lower() : name);

    filterByName(Names, DICtx.compile_units(), OS);
    filterByName(Names, DICtx.dwo_compile_units(), OS);
    return true;
  }

  // Handle the --find option and lower it to --debug-info=<offset>.
  if (!Find.empty()) {
    filterByAccelName(Find, DICtx, OS);
    return true;
  }

  // Dump the complete DWARF structure.
  DICtx.dump(OS, getDumpOpts(), DumpOffsets);
  return true;
}

void llvm::report_fatal_error(const Twine &Reason, bool GenCrashDiag) {
  llvm::fatal_error_handler_t handler = nullptr;
  void* handlerData = nullptr;
  {
    // Only acquire the mutex while reading the handler, so as not to invoke a
    // user-supplied callback under a lock.
#if LLVM_ENABLE_THREADS == 1
    std::lock_guard<std::mutex> Lock(ErrorHandlerMutex);
#endif
    handler = ErrorHandler;
    handlerData = ErrorHandlerUserData;
  }

  if (handler) {
    handler(handlerData, Reason.str(), GenCrashDiag);
  } else {
    // Blast the result out to stderr.  We don't try hard to make sure this
    // succeeds (e.g. handling EINTR) and we can't use errs() here because
    // raw ostreams can call report_fatal_error.
    SmallVector<char, 64> Buffer;
    raw_svector_ostream OS(Buffer);
    OS << "LLVM ERROR: " << Reason << "\n";
    StringRef MessageStr = OS.str();
    ssize_t written = ::write(2, MessageStr.data(), MessageStr.size());
    (void)written; // If something went wrong, we deliberately just give up.
  }

  // If we reached here, we are failing ungracefully. Run the interrupt handlers
  // to make sure any special cleanups get done, in particular that we remove
  // files registered with RemoveFileOnSignal.
  sys::RunInterruptHandlers();

  exit(1);
}