[llvm] [RISCV] Add an implementation of findRepresentativeClass to assign i32 to GPRRegClass for RV64. (PR #116165)

[Alex Bradbury via llvm-commits]

https://github.com/asb approved this pull request.

LGTM. I can't claim deep familiarity with the particular code path here, but your explanation and implementation make sense to me.

https://github.com/llvm/llvm-project/pull/116165