[llvm] [DAGCombiner] Add combine for vector interleave of splats (PR #151110)

[Min-Yih Hsu via llvm-commits]

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@@ -25173,6 +25173,37 @@ static SDValue combineConcatVectorOfCasts(SDNode *N, SelectionDAG &DAG) {
   return DAG.getNode(CastOpcode, DL, VT, NewConcat);
 }
 
+static SDValue combineConcatVectorInterleave(SDNode *N, SelectionDAG &DAG) {
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mshockwave wrote:

could you add a comment here to briefly explain your pattern?

https://github.com/llvm/llvm-project/pull/151110