[llvm] [DAGCombiner][RISCV] Preserve disjoint flag in folding (shl (or x, c1), c2) -> (or (shl x, c2), c1 << c2) (PR #76860)

[Nikita Popov via llvm-commits]

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

LGTM. Proof: https://alive2.llvm.org/ce/z/_2Bzdd

https://github.com/llvm/llvm-project/pull/76860