[llvm] [DAG] foldCONCAT_VECTORS - fold concat_vectors(v1xX insertelt(v,e,0), ...) -> build_vector(e,...) (PR #163420)

[Craig Topper via llvm-commits]

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@@ -6416,6 +6416,10 @@ static SDValue foldCONCAT_VECTORS(const SDLoc &DL, EVT VT,
       Elts.append(OpVT.getVectorNumElements(), DAG.getUNDEF(SVT));
     else if (Op.getOpcode() == ISD::BUILD_VECTOR)
       Elts.append(Op->op_begin(), Op->op_end());
+    else if (Op.getOpcode() == ISD::INSERT_VECTOR_ELT &&
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topperc wrote:

Update the comment above this loop?

https://github.com/llvm/llvm-project/pull/163420