[llvm] [SelectionDAG] Convert to or mask if all insertions are -1 (PR #138213)

[Matt Arsenault via llvm-commits]

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@@ -22987,6 +22986,19 @@ SDValue DAGCombiner::visitINSERT_VECTOR_ELT(SDNode *N) {
                            DAG.getBuildVector(VT, DL, Mask));
       }
 
+      // If all insertions are -1, try to convert to OR mask.
+      if (!LegalOperations && llvm::isAllOnesConstant(InVal) &&
+          all_of(Ops, [InVal](SDValue Op) { return !Op || Op == InVal; }) &&
+          count_if(Ops, [InVal](SDValue Op) { return Op == InVal; }) >= 2) {
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arsenm wrote:

Most of this is the same as the previous, merge them?

https://github.com/llvm/llvm-project/pull/138213