[DAG] canCreateUndefOrPoison - explicitly state the AssertSext/Zext/Align/NoFPClass can create poison. NFC. (llvm#146493)

This keeps getting forgotten (e.g. llvm#66603) - so make a point of adding
it here to make it clear instead of relying on the implicit default of
returning true.

Author: RKSimon

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

@@ -5522,6 +5522,13 @@ bool SelectionDAG::canCreateUndefOrPoison(SDValue Op, const APInt &DemandedElts,
 
   unsigned Opcode = Op.getOpcode();
   switch (Opcode) {
+  case ISD::AssertSext:
+  case ISD::AssertZext:
+  case ISD::AssertAlign:
+  case ISD::AssertNoFPClass:
+    // Assertion nodes can create poison if the assertion fails.
+    return true;
+
   case ISD::FREEZE:
   case ISD::CONCAT_VECTORS:
   case ISD::INSERT_SUBVECTOR: