[llvm] [RISCV][llvm-mca] Add llvm-mca tests for SiFive7 Vector Integer Arith… (PR #65283)

[Wang Pengcheng via llvm-commits]

https://github.com/wangpc-pp approved this pull request.

LGTM.
(maybe we should develop a test generator just like what we have in https://github.com/riscv-non-isa/rvv-intrinsic-doc/tree/main/rvv-intrinsic-generator?)

https://github.com/llvm/llvm-project/pull/65283