[llvm] [DAGCombiner][RISCV] Add target hook to decide hoisting LogicOp with extension (PR #136677)

[Jim Lin via llvm-commits]

tclin914 wrote:

> Doesn't InstCombine do the same transform as isDesirableToHoistLogicOpWithExt? https://godbolt.org/z/rM3dWh83e
> 
> Do we have a transform to turn it back into (or disjoint (sext/zext a), (sext/zext b))? If not then this patch isn't all that useful by itself.

Keep disjoint https://github.com/llvm/llvm-project/pull/136815 if it is transformed during InstCombine.

https://github.com/llvm/llvm-project/pull/136677