Method parseUseLists

src/lib/Bitcode/Reader/BitcodeReader.cpp:2644–2707

}

Error BitcodeReader::parseUseLists() {
  if (Stream.EnterSubBlock(bitc::USELIST_BLOCK_ID))
    return error("Invalid record");

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

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

    switch (Entry.Kind) {
    case BitstreamEntry::SubBlock: // Handled for us already.
    case BitstreamEntry::Error:
      return error("Malformed block");
    case BitstreamEntry::EndBlock:
      return Error::success();
    case BitstreamEntry::Record:
      // The interesting case.
      break;
    }

    // Read a use list record.
    Record.clear();
    bool IsBB = false;
    switch (Stream.readRecord(Entry.ID, Record)) {
    default:  // Default behavior: unknown type.
      break;
    case bitc::USELIST_CODE_BB:
      IsBB = true;
      LLVM_FALLTHROUGH;
    case bitc::USELIST_CODE_DEFAULT: {
      unsigned RecordLength = Record.size();
      if (RecordLength < 3)
        // Records should have at least an ID and two indexes.
        return error("Invalid record");
      unsigned ID = Record.back();
      Record.pop_back();

      Value *V;
      if (IsBB) {
        assert(ID < FunctionBBs.size() && "Basic block not found");
        V = FunctionBBs[ID];
      } else
        V = ValueList[ID];
      unsigned NumUses = 0;
      SmallDenseMap<const Use *, unsigned, 16> Order;
      for (const Use &U : V->materialized_uses()) {
        if (++NumUses > Record.size())
          break;
        Order[&U] = Record[NumUses - 1];
      }
      if (Order.size() != Record.size() || NumUses > Record.size())
        // Mismatches can happen if the functions are being materialized lazily
        // (out-of-order), or a value has been upgraded.
        break;

      V->sortUseList([&](const Use &L, const Use &R) {
        return Order.lookup(&L) < Order.lookup(&R);