[SelectionDAG] Add AssertAlign to AddNodeIDCustom so that it will CSE properly.

[craig.topper]

Summary

The alignment needs to be part of the folding set hash. This is
handled by getAssertAlign when nodes are created, but needs to repeated here.

No test case as I found it as part of a very early experimental patch.

[spatel]

LGTM

llvm/lib/CodeGen/SelectionDAG/SelectionDAG.cpp

static void AddNodeIDCustom(FoldingSetNodeID &ID, const SDNode *N) {
   case ISD::TargetBlockAddress:
   case ISD::BlockAddress: {
     const BlockAddressSDNode *BA = cast<BlockAddressSDNode>(N);
     ID.AddPointer(BA->getBlockAddress());
     ID.AddInteger(BA->getOffset());
     ID.AddInteger(BA->getTargetFlags());
     break;
   }
+  case ISD::AssertAlign:
+    ID.AddInteger(cast<AssertAlignSDNode>(N)->getAlign().value());
+    break;
   } // end switch (N->getOpcode())
 
   // Target specific memory nodes could also have address spaces and flags
   // to check.
   if (N->isTargetMemoryOpcode()) {
     const MemSDNode *MN = cast<MemSDNode>(N);
     ID.AddInteger(MN->getPointerInfo().getAddrSpace());
     ID.AddInteger(MN->getMemOperand()->getFlags());