[llvm] [RISCV][WIP] Fold (sh3add Z, (add X, (slli Y, 6))) -> (sh3add (sh3add Y, Z), X). (PR #85734)

[Craig Topper via llvm-commits]

topperc wrote:

Here's example IR extracted from the benchmark https://godbolt.org/z/fxc688sbG

https://github.com/llvm/llvm-project/pull/85734