[clang] [llvm] [RISCV] Add processor definition for SpacemiT-X60 (PR #94564)

[Yingwei Zheng via llvm-commits]

https://github.com/dtcxzyw approved this pull request.

LGTM. But I think it needs a double check by spacemit staffs.


https://github.com/llvm/llvm-project/pull/94564