[llvm] [RISCV][TTI] Implement instruction cost for vp.reduce.* (PR #114184)

[Elvis Wang via llvm-commits]

ElvisWang123 wrote:

> I am not sure the fully duplicated test coverage for vp.reduce is justified here. The whole point of this change is that they're cost just like normal reduces? Why do we need to complete double all test coverage?

The test cases here want to make sure the instruction costs for vp intrinsics are same as their non-vp counterpart.

Adding `type-based-intrinsic-cost=true` let the printer class query the cost model without values which align to how loop vectorizer query the instruction costs.


https://github.com/llvm/llvm-project/pull/114184