llvm dev - Aug 2020 - How to get C++ Class type from .bc file

Hello, looking at the data type definition in llvm:Type Class,there is no C++
class/STL/string and other high level language types.I would like to ask if I
need to get these data types from .bc file,do I need to expand the llvm type
myself? Or can I just invoke an existing combination of functions to get it,such
as whether I can process a class type to basic type step by step.If it can get
with existing functions,please provide a link on how to use. Thank you very
much.