[llvm] [RISCV] Enhance RISCVMoveMerger for GPRPair Moves on RV32 #180831 (PR #182416)

[Sam Elliott via llvm-commits]

https://github.com/lenary commented:

I'm slightly concerned there are no cases where we introduce a move pair where one of the GPRPair operands *isn't* `a0`/`a1`. If we don't have a case for these already, can you write a MIR testcase to show that this works?

https://github.com/llvm/llvm-project/pull/182416