Attributor: Add isAtFixpoint part of nofpclass handling

Author: arsenm

llvm/lib/Transforms/IPO/AttributorAttributes.cpp

@@ -10281,6 +10281,9 @@ struct AANoFPClassFloating : public AANoFPClassImpl {
   /// See AbstractAttribute::initialize(...).
   void initialize(Attributor &A) override {
     AANoFPClassImpl::initialize(A);
+    if (!getState().isAtFixpoint())
+      if (Instruction *CtxI = getCtxI())
+        followUsesInMBEC(*this, A, getState(), *CtxI);
   }
 
   /// See AbstractAttribute::updateImpl(...).