Method parseValueSymbolTable

src/lib/Bitcode/Reader/BitcodeReader.cpp:1949–2045

Parse the value symbol table at either the current parsing location or at the given bit offset if provided.

/// Parse the value symbol table at either the current parsing location or
/// at the given bit offset if provided.
Error BitcodeReader::parseValueSymbolTable(uint64_t Offset) {
  uint64_t CurrentBit;
  // Pass in the Offset to distinguish between calling for the module-level
  // VST (where we want to jump to the VST offset) and the function-level
  // VST (where we don't).
  if (Offset > 0) {
    CurrentBit = jumpToValueSymbolTable(Offset, Stream);
    // If this module uses a string table, read this as a module-level VST.
    if (UseStrtab) {
      if (Error Err = parseGlobalValueSymbolTable())
        return Err;
      Stream.JumpToBit(CurrentBit);
      return Error::success();
    }
    // Otherwise, the VST will be in a similar format to a function-level VST,
    // and will contain symbol names.
  }

  // Compute the delta between the bitcode indices in the VST (the word offset
  // to the word-aligned ENTER_SUBBLOCK for the function block, and that
  // expected by the lazy reader. The reader's EnterSubBlock expects to have
  // already read the ENTER_SUBBLOCK code (size getAbbrevIDWidth) and BlockID
  // (size BlockIDWidth). Note that we access the stream's AbbrevID width here
  // just before entering the VST subblock because: 1) the EnterSubBlock
  // changes the AbbrevID width; 2) the VST block is nested within the same
  // outer MODULE_BLOCK as the FUNCTION_BLOCKs and therefore have the same
  // AbbrevID width before calling EnterSubBlock; and 3) when we want to
  // jump to the FUNCTION_BLOCK using this offset later, we don't want
  // to rely on the stream's AbbrevID width being that of the MODULE_BLOCK.
  unsigned FuncBitcodeOffsetDelta =
      Stream.getAbbrevIDWidth() + bitc::BlockIDWidth;

  if (Stream.EnterSubBlock(bitc::VALUE_SYMTAB_BLOCK_ID))
    return error("Invalid record");

  SmallVector<uint64_t, 64> Record;

  Triple TT(TheModule->getTargetTriple());

  // Read all the records for this value table.
  SmallString<128> ValueName;

  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:
      if (Offset > 0)
        Stream.JumpToBit(CurrentBit);
      return Error::success();
    case BitstreamEntry::Record:
      // The interesting case.
      break;
    }