[llvm] [RISCV] Combine (addi (addi)) and add post riscv-opt-w-instrs machine-combiner (PR #171165)

[Piotr Fusik via llvm-commits]

pfusik wrote:

> Would that undo the benefit what we were trying to do with 3a2c8f7af8b38dd17649a42fc1f291d47f6e175d?

[It does](https://github.com/llvm/llvm-project/pull/171165/commits/70618ca29f5011f2b4b8b8216b5c8fd68110ebdc#diff-c22b65af9273b6203158c74f7efe8845d72d621a771b7ddb9550fa5f6ac19f45L1079). :(

https://github.com/llvm/llvm-project/pull/171165