[llvm] [RISCV] Eliminate redundant materializations after register comparison (PR #227673)

[via llvm-commits]

tinfengyu wrote:

Thanks! I've restructured the PR into two commits as requested. The first commit adds the new tests with checks generated by update_mir_test_checks.py, and the second commit contains the codegen changes and updates the tests to show the optimized output. I've force-pushed the restructured history.

https://github.com/llvm/llvm-project/pull/227673