[llvm] [RISCV][GISEL] instruction-select for G_SPLAT_VECTOR (PR #111193)

[Craig Topper via llvm-commits]

topperc wrote:

> Sure I trust you. But you build the G_CONSTANT just for:
> 
> ```
> int64_t CstVal = MI.getOperand(1).getCImm()->getSExtValue();
> ```

I didn't notice what render function you pasted there. That's unrelated to this patch. It's used by our scalar ADDIW/SRLIW/SRAIW/SLLIW to hack around some weird type inferencing issues. GISel has i32 as a legal type for RV64, SelectionDAG doesn't. See #68470

https://github.com/llvm/llvm-project/pull/111193