Function readIdentificationBlock

src/lib/Bitcode/Reader/BitcodeReader.cpp:167–209

Read the "IDENTIFICATION_BLOCK_ID" block, do some basic enforcement on the "epoch" encoded in the bitcode, and return the producer name if any.

/// Read the "IDENTIFICATION_BLOCK_ID" block, do some basic enforcement on the
/// "epoch" encoded in the bitcode, and return the producer name if any.
static Expected<std::string> readIdentificationBlock(BitstreamCursor &Stream) {
  if (Stream.EnterSubBlock(bitc::IDENTIFICATION_BLOCK_ID))
    return error("Invalid record");

  // Read all the records.
  SmallVector<uint64_t, 64> Record;

  std::string ProducerIdentification;

  while (true) {
    BitstreamEntry Entry = Stream.advance();

    switch (Entry.Kind) {
    default:
    case BitstreamEntry::Error:
      return error("Malformed block");
    case BitstreamEntry::EndBlock:
      return ProducerIdentification;
    case BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read a record.
    Record.clear();
    unsigned BitCode = Stream.readRecord(Entry.ID, Record);
    switch (BitCode) {
    default: // Default behavior: reject
      return error("Invalid value");
    case bitc::IDENTIFICATION_CODE_STRING: // IDENTIFICATION: [strchr x N]
      convertToString(Record, 0, ProducerIdentification);
      break;
    case bitc::IDENTIFICATION_CODE_EPOCH: { // EPOCH: [epoch#]
      unsigned epoch = (unsigned)Record[0];
      if (epoch != bitc::BITCODE_CURRENT_EPOCH) {
        return error(
          Twine("Incompatible epoch: Bitcode '") + Twine(epoch) +
          "' vs current: '" + Twine(bitc::BITCODE_CURRENT_EPOCH) + "'");
      }
    }
    }
  }
}

static Expected<std::string> readIdentificationCode(BitstreamCursor &Stream) {
  // We expect a number of well-defined blocks, though we don't necessarily