minor change

Author: diggerlin

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -7586,14 +7586,6 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     }
   }
 
-  /*
-  if (N2.getOpcode() == ISD::POISON) {
-    switch (Opcode) {
-    case ISD::ADD:
-      return getPOISON(VT);
-    }
-  }*/
-
   // Fold a bunch of operators when the RHS is undef.
   if (N2.isUndef()) {
     switch (Opcode) {
@@ -7609,16 +7601,18 @@ SDValue SelectionDAG::getNode(unsigned Opcode, const SDLoc &DL, EVT VT,
     case ISD::SDIV:
     case ISD::UREM:
     case ISD::SREM:
+      // fold op(arg1, undef) -> undef, // fold op(arg1, poison) -> poison.
       return N2.getOpcode() == ISD::POISON
                  ? getPOISON(VT)
-                 : getUNDEF(VT); // fold op(arg1, undef) -> undef
+                 : getUNDEF(VT);
     case ISD::MUL:
     case ISD::AND:
     case ISD::SSUBSAT:
     case ISD::USUBSAT:
+       // fold op(arg1, undef) -> 0, fold op(arg1, poison) -> poison.
       return N2.getOpcode() == ISD::POISON
                  ? getPOISON(VT)
-                 : getConstant(0, DL, VT); // fold op(arg1, undef) -> 0
+                 : getConstant(0, DL, VT)
     case ISD::OR:
     case ISD::SADDSAT:
     case ISD::UADDSAT: