[clang] [llvm] [RISCV] Add support for experimental Zimop extension (PR #74824)

[Yingwei Zheng via cfe-commits]

dtcxzyw wrote:

I guess you should split it into patch series.
+ [ ] MC support (and docs)
+ [ ] Sched support
+ [ ] ISel support
+ [ ] Builtin intrinsic support in clang


https://github.com/llvm/llvm-project/pull/74824