I have a problem about "Writting an LLVM Backend"

I intend to write a new LLVM Backend for my new instruction set,but I notice that the example in the document “Writing an LLVM Backend” is not suitable for up-to-date version”7.0.1”.

That document is in “docs” directory of LLVM source of up-to-date version and LLVM Website.

For example,in section “Target Machine”,in “SparcTargetMachine.h”,there is “DataLayout”,”InstrInfo” as class members in class “SparcTargetMachine” but is not in “SparcTargetMachine.h” which is in “LLVM version 7.0.1”,and the argument list of the constructor is also different.

I don’t know how to write a new LLVM Backend for me.**Do you have new documents suitable for up-to-date version?**or,do you know what version of LLVM is for that documents?

You can find an almost [1] up to date set of patches used to create a
RISC-V backend from scratch at:

https://github.com/lowRISC/riscv-llvm

[1] hasn't been rebased for about 11 months.