[clang] [llvm] [RISCV] Add processor definition and scheduling information for GR765 (PR #225638)

[Daniel Cederman via llvm-commits]

doac wrote:

Thank you for all the comments!

I wasn't sure what the philosophy was for which extensions to list. I saw some processor models include privileged extensions so I added them, but it makes sense to skip them for the compiler.

The Zf* extensions should be there. For a more detailed list see chapter 116 in the IP manual https://download.gaisler.com/products/GRLIB/doc/grip.pdf

- Added gaisler- vendor prefix.
- Removed scheduling info.
- Removed privileged extensions.
- Replaced Zba, Zbb, and Zbs with B.
- Rewrote extension print test to match other targets.
- Moved release note to end.
- Fixed TunePostRAScheduler indentation.

https://github.com/llvm/llvm-project/pull/225638