//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// // // This interface is used to build and manipulate a call graph, which is a very // useful tool for interprocedural optimization. // // Every function in a module is represented as a node in the call graph. The // callgraph node keeps track of which functions the are called by the function // corresponding to the node. // // A call graph may contain nodes where the function that they correspond to is // null. These 'external' nodes are used to represent control flow that is not // represented (or analyzable) in the module. In particular, this analysis // builds one external node such that: // 1. All functions in the module without internal linkage will have edges // from this external node, indicating that they could be called by // functions outside of the module. // 2. All functions whose address is used for something more than a direct // call, for example being stored into a memory location will also have an // edge from this external node. Since they may be called by an unknown // caller later, they must be tracked as such. // // There is a second external node added for calls that leave this module. // Functions have a call edge to the external node iff: // 1. The function is external, reflecting the fact that they could call // anything without internal linkage or that has its address taken. // 2. The function contains an indirect function call. // // As an extension in the future, there may be multiple nodes with a null // function. These will be used when we can prove (through pointer analysis) // that an indirect call site can call only a specific set of functions. // // Because of these properties, the CallGraph captures a conservative superset // of all of the caller-callee relationships, which is useful for // transformations. // // The CallGraph class also attempts to figure out what the root of the // CallGraph is, which it currently does by looking for a function named 'main'. // If no function named 'main' is found, the external node is used as the entry // node, reflecting the fact that any function without internal linkage could // be called into (which is common for libraries). // //===----------------------------------------------------------------------===// #ifndef LLVM_ANALYSIS_CALLGRAPH_H #define LLVM_ANALYSIS_CALLGRAPH_H #include "llvm/ADT/GraphTraits.h" #include "llvm/ADT/STLExtras.h" #include "llvm/Pass.h" #include "llvm/Support/CallSite.h" namespace llvm { class Function; class Module; class CallGraphNode; //===----------------------------------------------------------------------===// // CallGraph class definition // class CallGraph { protected: Module *Mod; // The module this call graph represents typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; FunctionMapTy FunctionMap; // Map from a function to its node public: static char ID; // Class identification, replacement for typeinfo //===--------------------------------------------------------------------- // Accessors... // typedef FunctionMapTy::iterator iterator; typedef FunctionMapTy::const_iterator const_iterator; /// getModule - Return the module the call graph corresponds to. /// Module &getModule() const { return *Mod; } 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(); } // Subscripting operators, return the call graph node for the provided // function inline const CallGraphNode *operator[](const Function *F) const { const_iterator I = FunctionMap.find(F); assert(I != FunctionMap.end() && "Function not in callgraph!"); return I->second; } inline CallGraphNode *operator[](const Function *F) { const_iterator I = FunctionMap.find(F); assert(I != FunctionMap.end() && "Function not in callgraph!"); return I->second; } //Returns the CallGraphNode which is used to represent undetermined calls // into the callgraph. Override this if you want behavioural inheritance. virtual CallGraphNode* getExternalCallingNode() const { return 0; } //Return the root/main method in the module, or some other root node, such // as the externalcallingnode. Overload these if you behavioural // inheritance. virtual CallGraphNode* getRoot() { return 0; } virtual const CallGraphNode* getRoot() const { return 0; } //===--------------------------------------------------------------------- // Functions to keep a call graph up to date with a function that has been // modified. // /// removeFunctionFromModule - Unlink the function from this module, returning /// it. Because this removes the function from the module, the call graph /// node is destroyed. This is only valid if the function does not call any /// other functions (ie, there are no edges in it's CGN). The easiest way to /// do this is to dropAllReferences before calling this. /// Function *removeFunctionFromModule(CallGraphNode *CGN); Function *removeFunctionFromModule(Function *F) { return removeFunctionFromModule((*this)[F]); } /// changeFunction - This method changes the function associated with this /// CallGraphNode, for use by transformations that need to change the /// prototype of a Function (thus they must create a new Function and move the /// old code over). void changeFunction(Function *OldF, Function *NewF); /// getOrInsertFunction - This method is identical to calling operator[], but /// it will insert a new CallGraphNode for the specified function if one does /// not already exist. CallGraphNode *getOrInsertFunction(const Function *F); //===--------------------------------------------------------------------- // Pass infrastructure interface glue code... // protected: CallGraph() {} public: virtual ~CallGraph() { destroy(); } /// initialize - Call this method before calling other methods, /// re/initializes the state of the CallGraph. /// void initialize(Module &M); virtual void print(std::ostream &o, const Module *M) const; void print(std::ostream *o, const Module *M) const { if (o) print(*o, M); } void dump() const; // stub - dummy function, just ignore it static int stub; protected: // destroy - Release memory for the call graph virtual void destroy(); }; //===----------------------------------------------------------------------===// // CallGraphNode class definition // class CallGraphNode { Function *F; typedef std::pair<CallSite,CallGraphNode*> CallRecord; std::vector<CallRecord> CalledFunctions; CallGraphNode(const CallGraphNode &); // Do not implement public: //===--------------------------------------------------------------------- // Accessor methods... // typedef std::vector<CallRecord>::iterator iterator; typedef std::vector<CallRecord>::const_iterator const_iterator; // getFunction - Return the function that this call graph node represents... Function *getFunction() const { return F; } inline iterator begin() { return CalledFunctions.begin(); } inline iterator end() { return CalledFunctions.end(); } inline const_iterator begin() const { return CalledFunctions.begin(); } inline const_iterator end() const { return CalledFunctions.end(); } inline bool empty() const { return CalledFunctions.empty(); } inline unsigned size() const { return CalledFunctions.size(); } // Subscripting operator - Return the i'th called function... // CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i].second; } /// dump - Print out this call graph node. /// void dump() const; void print(std::ostream &OS) const; void print(std::ostream *OS) const { if (OS) print(*OS); } //===--------------------------------------------------------------------- // Methods to keep a call graph up to date with a function that has been // modified // /// removeAllCalledFunctions - As the name implies, this removes all edges /// from this CallGraphNode to any functions it calls. void removeAllCalledFunctions() { CalledFunctions.clear(); } /// addCalledFunction add a function to the list of functions called by this /// one. void addCalledFunction(CallSite CS, CallGraphNode *M) { CalledFunctions.push_back(std::make_pair(CS, M)); } /// removeCallEdgeTo - This method removes a *single* edge to the specified /// callee function. Note that this method takes linear time, so it should be /// used sparingly. void removeCallEdgeTo(CallGraphNode *Callee); /// removeAnyCallEdgeTo - This method removes any call edges from this node to /// the specified callee function. This takes more time to execute than /// removeCallEdgeTo, so it should not be used unless necessary. void removeAnyCallEdgeTo(CallGraphNode *Callee); friend class CallGraph; // CallGraphNode ctor - Create a node for the specified function. inline CallGraphNode(Function *f) : F(f) {} }; //===----------------------------------------------------------------------===// // GraphTraits specializations for call graphs so that they can be treated as // graphs by the generic graph algorithms. // // Provide graph traits for tranversing call graphs using standard graph // traversals. template <> struct GraphTraits<CallGraphNode*> { typedef CallGraphNode NodeType; typedef std::pair<CallSite, CallGraphNode*> CGNPairTy; typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; static inline ChildIteratorType child_begin(NodeType *N) { return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); } static inline ChildIteratorType child_end (NodeType *N) { return map_iterator(N->end(), CGNDerefFun(CGNDeref)); } static CallGraphNode *CGNDeref(CGNPairTy P) { return P.second; } }; template <> struct GraphTraits<const CallGraphNode*> { typedef const CallGraphNode NodeType; typedef NodeType::const_iterator ChildIteratorType; static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } }; template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { static NodeType *getEntryNode(CallGraph *CGN) { return CGN->getExternalCallingNode(); // Start at the external node! } typedef std::pair<const Function*, CallGraphNode*> PairTy; typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; // nodes_iterator/begin/end - Allow iteration over all nodes in the graph typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; static nodes_iterator nodes_begin(CallGraph *CG) { return map_iterator(CG->begin(), DerefFun(CGdereference)); } static nodes_iterator nodes_end (CallGraph *CG) { return map_iterator(CG->end(), DerefFun(CGdereference)); } static CallGraphNode &CGdereference(PairTy P) { return *P.second; } }; template<> struct GraphTraits<const CallGraph*> : public GraphTraits<const CallGraphNode*> { static NodeType *getEntryNode(const CallGraph *CGN) { return CGN->getExternalCallingNode(); } // nodes_iterator/begin/end - Allow iteration over all nodes in the graph typedef CallGraph::const_iterator nodes_iterator; static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } }; } // End llvm namespace // Make sure that any clients of this file link in CallGraph.cpp FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) #endif