What are * .td files in LLVM / Clang source?

Question

I only recognize the structure of the LLVM / Clang source code, and it’s hard for me to understand that there really are * .td files.

Answer 1

*. td files contain TableGen code. TableGen is an interpreted language for describing "records of domain-related information." One of its main goals is to generate parts of the Llvm / clang C / C ++ source code. However, it is used for other purposes, see
TableGen Program Reference: http://llvm.org/docs/TableGen/index.html
TableGen Language Reference: http://llvm.org/docs/TableGen/LangRef.html
TableGen Backends: http://llvm.org/docs/TableGen/BackEnds.html