[llvm] Avoid making vector more poisonous in visitCONCAT_VECTORS (PR #223492)

[Björn Pettersson via llvm-commits]

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@@ -27243,7 +27243,9 @@ static SDValue combineConcatVectorOfConcatVectors(SDNode *N,
   SmallVector<SDValue> ConcatOps;
   for (const SDValue &Op : N->ops()) {
     if (Op.isUndef()) {
-      ConcatOps.append(FirstConcat->getNumOperands(), DAG.getPOISON(SubVT));
+      SDValue Fill = Op.getOpcode() == ISD::POISON ? DAG.getPOISON(SubVT)
+                                                   : DAG.getUNDEF(SubVT);
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bjope wrote:

Yes. I've updated the patch to use getNode.

https://github.com/llvm/llvm-project/pull/223492