[llvm] [RISCV] Add LUI/AUIPC+ADDI fusions to sifive-p450. (PR #78501)

[Philip Reames via llvm-commits]

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

LGTM

Any chance there's a public doc which mentions this you can point to?  Non blocking, just asking for the record.

https://github.com/llvm/llvm-project/pull/78501