Simplify pattern match

Author: ckoparkar

llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp

@@ -6201,14 +6201,13 @@ SDValue DAGCombiner::visitIMINMAX(SDNode *N) {
 
   // (umin (sub a, b) a) -> (usubo a, b); (select usubo.1, a, usubo.0)
   {
-    SDValue A, B;
-    if (sd_match(N0, m_Sub(m_Value(A), m_Value(B))) &&
-        sd_match(N1, m_Specific(A)) &&
+    SDValue B;
+    if (sd_match(N0, m_Sub(m_Specific(N1), m_Value(B))) &&
         TLI.isOperationLegalOrCustom(ISD::USUBO, VT)) {
       EVT SETCCT = getSetCCResultType(VT);
       SDVTList VTs = DAG.getVTList(VT, SETCCT);
-      SDValue USO = DAG.getNode(ISD::USUBO, DL, VTs, A, B);
-      return DAG.getSelect(DL, VT, USO.getValue(1), A, USO.getValue(0));
+      SDValue USO = DAG.getNode(ISD::USUBO, DL, VTs, N1, B);
+      return DAG.getSelect(DL, VT, USO.getValue(1), N1, USO.getValue(0));
     }
   }