[DAG] canCreateUndefOrPoison - remove isGuaranteedNotToBeUndefOrPoison check for shift nodes (#146502)

No longer necessary now that #146490 has landed - we still have the test coverage from #94145 that covers this.

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5623,9 +5623,7 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
   case ISD::SRA:
     // If the max shift amount isn't in range, then the shift can
     // create poison.
-    return !isGuaranteedNotToBeUndefOrPoison(Op.getOperand(1), DemandedElts,
-                                             PoisonOnly, Depth + 1) ||
-           !getValidMaximumShiftAmount(Op, DemandedElts, Depth + 1);
+    return !getValidMaximumShiftAmount(Op, DemandedElts, Depth + 1);
 
   case ISD::CTTZ_ZERO_UNDEF:
   case ISD::CTLZ_ZERO_UNDEF: