[llvm] [SelectionDAG] WidenVecOp_INSERT_SUBVECTOR - Replace `INSERT_SUBVECTOR` with series of `INSERT_VECTOR_ELT` (PR #124420)

[Simon Pilgrim via llvm-commits]

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@@ -7040,8 +7040,11 @@ SDValue DAGTypeLegalizer::WidenVecOp_INSERT_SUBVECTOR(SDNode *N) {
   SDValue SubVec = N->getOperand(1);
   SDValue InVec = N->getOperand(0);
 
-  if (getTypeAction(SubVec.getValueType()) == TargetLowering::TypeWidenVector)
+  EVT OrigVT;
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RKSimon wrote:

Pull this out - no need to limit it the widencase - `EVT OrigVT = SubVec.getValueType();`

https://github.com/llvm/llvm-project/pull/124420