[llvm] [RISCV] Combine (vp.splice (insert_elt poison, scalar, 0), vec, 0, mask, 1, vl) to vslide1up. (PR #144871)

[Pengcheng Wang via llvm-commits]

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@@ -17601,6 +17601,36 @@ static SDValue performFP_TO_INT_SATCombine(SDNode *N,
   return DAG.getSelectCC(DL, Src, Src, ZeroInt, FpToInt, ISD::CondCode::SETUO);
 }
 
+static SDValue performVSLIDEUPOrDOWNCombine(SDNode *N, SelectionDAG &DAG) {
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wangpc-pp wrote:

performVSLIDEUPOrDOWNCombine -> performVSLIDECombine?

https://github.com/llvm/llvm-project/pull/144871