Function parseSectionHeader

lib/Bytecode/Reader/BytecodeReader.cpp:331–372

Parses the section header from the bytecode.

/// Parses the section header from the bytecode.
static LogicalResult parseSectionHeader(EncodingReader &reader,
                                        SectionHeader &header,
                                        MLIRContext &context) {
  if (reader.remaining() < 1)
    return reader.emitError()
           << "unexpected end of data while reading section header";
  uint8_t idAndIsAligned;
  if (failed(reader.readLE(idAndIsAligned)))
    return reader.emitError() << "failed to read section ID and alignment flag";
  header.sectionID = idAndIsAligned & 0x7F;
  header.hasAlignment = (idAndIsAligned & 0x80) != 0;

  // If this is the end section marker, return success.
  if (header.sectionID == Section::EndOfBytecode) {
    if (header.hasAlignment)
      return reader.emitError()
             << "end section should not have alignment flag set";
    return success();
  }
  if (header.sectionID >= Section::NumSections)
    return reader.emitError() << "unknown section ID: " << header.sectionID;

  // Read the section length.
  if (failed(reader.readVarInt(header.length)))
    return reader.emitError() << "failed to read section length";
  if (header.length > reader.remaining())
    return reader.emitError()
           << "section length " << header.length
           << " exceeds remaining data size " << reader.remaining();

  // If the section is aligned, read the alignment value and adjust the buffer.
  if (header.hasAlignment) {
    if (failed(reader.readVarInt(header.alignment)))
      return failure();
    if (header.alignment == 0 || !llvm::isPowerOf2_64(header.alignment))
      return reader.emitError()
             << "invalid alignment value: " << header.alignment;
    if (failed(reader.skipPadding(header.alignment)))
      return failure();
  }
  return success();
}

//===----------------------------------------------------------------------===//
// String Section