[CallGraph] Add invalidate method.

[asbirlea]

Summary

Add invalidate method in CallGraph.

llvm/include/llvm/Analysis/CallGraph.h

public:
   void dump() const;
 
   using iterator = FunctionMapTy::iterator;
   using const_iterator = FunctionMapTy::const_iterator;
 
   /// Returns the module the call graph corresponds to.
   Module &getModule() const { return M; }
 
+  bool invalidate(Module &M, const PreservedAnalyses &PA,
+                  ModuleAnalysisManager::Invalidator &);
+
   inline iterator begin() { return FunctionMap.begin(); }
   inline iterator end() { return FunctionMap.end(); }
   inline const_iterator begin() const { return FunctionMap.begin(); }
   inline const_iterator end() const { return FunctionMap.end(); }
 
   /// Returns the call graph node for the provided function.
   inline const CallGraphNode *operator[](const Function *F) const {
     const_iterator I = FunctionMap.find(F);

llvm/lib/Analysis/CallGraph.cpp

 // Reset all node's use counts to zero before deleting them to prevent an
 // assertion from firing.
 #ifndef NDEBUG
   for (auto &I : FunctionMap)
     I.second->allReferencesDropped();
 #endif
 }
 
+bool CallGraph::invalidate(Module &M, const PreservedAnalyses &PA,
+                           ModuleAnalysisManager::Invalidator &) {
+  auto PAC = PA.getChecker<CallGraphAnalysis>();
+  return !(PAC.preserved() || PAC.preservedSet<AllAnalysesOn<Module>>() ||
+           PAC.preservedSet<CFGAnalyses>());
+}
+
 void CallGraph::addToCallGraph(Function *F) {
   CallGraphNode *Node = getOrInsertFunction(F);
 
   // If this function has external linkage or has its address taken, anything
   // could call it.
   if (!F->hasLocalLinkage() || F->hasAddressTaken())
     ExternalCallingNode->addCalledFunction(nullptr, Node);