public void addLineNumber(char startPc, char lineNumber) {
        if (lineDebugInfo) {
            if (lineInfo.nonEmpty() && lineInfo.head[0] == startPc)
                lineInfo = lineInfo.tail;
            if (lineInfo.isEmpty() || lineInfo.head[1] != lineNumber)
                lineInfo = lineInfo.prepend(new char[]{startPc, lineNumber});
        }
    }