[llvm-branch-commits] [llvm] [SelectionDAG] Track demanded concat elements in noundef checks (PR #200932)

[Simon Pilgrim via llvm-branch-commits]

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@@ -5665,6 +5665,32 @@ bool SelectionDAG::isGuaranteedNotToBeUndefOrPoison(SDValue Op,
     }
     return true;
 
+  case ISD::CONCAT_VECTORS: {
+    if (!DemandedElts)
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RKSimon wrote:

why is this necessary?

https://github.com/llvm/llvm-project/pull/200932