[llvm] [RISCV] Use addi rather than addiw for immediates materialised by lui+addi(w) pairs when possible (PR #141663)

[Craig Topper via llvm-commits]

topperc wrote:

Can this pessimize RISCVOptWinstrs? Do we need to detect that LUI+ADDI is sign extended for most cases?

https://github.com/llvm/llvm-project/pull/141663