[SelectionDAG] Clean up some redundant setting of node flags (NFC) (#130307)

PR #130124 added a use of FlagInserter to the start of
SelectionDAGLegalize::PromoteNode, making some of the places where we
set flags be redundant, so remove them. The places where the setting of
flags remains are in non-floating-point operations.

Author: john-brawn-arm

llvm/lib/CodeGen/SelectionDAG/LegalizeDAG.cpp

@@ -5283,7 +5283,6 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
     Tmp3 = DAG.getNode(ExtOp, dl, NVT, Node->getOperand(2));
     // Perform the larger operation, then round down.
     Tmp1 = DAG.getSelect(dl, NVT, Tmp1, Tmp2, Tmp3);
-    Tmp1->setFlags(Node->getFlags());
     if (TruncOp != ISD::FP_ROUND)
       Tmp1 = DAG.getNode(TruncOp, dl, Node->getValueType(0), Tmp1);
     else
@@ -5412,8 +5411,7 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
   case ISD::FATAN2:
     Tmp1 = DAG.getNode(ISD::FP_EXTEND, dl, NVT, Node->getOperand(0));
     Tmp2 = DAG.getNode(ISD::FP_EXTEND, dl, NVT, Node->getOperand(1));
-    Tmp3 = DAG.getNode(Node->getOpcode(), dl, NVT, Tmp1, Tmp2,
-                       Node->getFlags());
+    Tmp3 = DAG.getNode(Node->getOpcode(), dl, NVT, Tmp1, Tmp2);
     Results.push_back(
         DAG.getNode(ISD::FP_ROUND, dl, OVT, Tmp3,
                     DAG.getIntPtrConstant(0, dl, /*isTarget=*/true)));
@@ -5524,8 +5522,7 @@ void SelectionDAGLegalize::PromoteNode(SDNode *Node) {
   case ISD::FSINCOS:
   case ISD::FSINCOSPI: {
     Tmp1 = DAG.getNode(ISD::FP_EXTEND, dl, NVT, Node->getOperand(0));
-    Tmp2 = DAG.getNode(Node->getOpcode(), dl, DAG.getVTList(NVT, NVT), Tmp1,
-                       Node->getFlags());
+    Tmp2 = DAG.getNode(Node->getOpcode(), dl, DAG.getVTList(NVT, NVT), Tmp1);
     Tmp3 = DAG.getIntPtrConstant(0, dl, /*isTarget=*/true);
     for (unsigned ResNum = 0; ResNum < Node->getNumValues(); ResNum++)
       Results.push_back(