[llvm] [RISCV] Add a pass to remove ADDI by reassociating to fold into load/store address. (PR #127151)

[Pengcheng Wang via llvm-commits]

https://github.com/wangpc-pp commented:

Is there an overlap between `RISCVMergeBaseOffset` and `RISCVFoldMemOffset`? Based on my rough understanding, they are doing similiar things, right?

https://github.com/llvm/llvm-project/pull/127151