[llvm] [SDAG] (setcc (sub nsw a, b), zero, s??) -> (setcc a, b, s??) (PR #175459)

[via llvm-commits]

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@@ -13893,6 +13893,13 @@ SDValue DAGCombiner::visitSETCC(SDNode *N) {
     return Combined;
   }
 
+  // (setcc (sub n?w a, b), zero, ?lt) -> (setcc a, b, ?lt)
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DaKnig wrote:

added proofs in the first message, using alive2

https://github.com/llvm/llvm-project/pull/175459