LLVM API Documentation
00001 //===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===// 00002 // 00003 // The LLVM Compiler Infrastructure 00004 // 00005 // This file was developed by the LLVM research group and is distributed under 00006 // the University of Illinois Open Source License. See LICENSE.TXT for details. 00007 // 00008 //===----------------------------------------------------------------------===// 00009 // 00010 // This interface is used to build and manipulate a call graph, which is a very 00011 // useful tool for interprocedural optimization. 00012 // 00013 // Every function in a module is represented as a node in the call graph. The 00014 // callgraph node keeps track of which functions the are called by the function 00015 // corresponding to the node. 00016 // 00017 // A call graph may contain nodes where the function that they correspond to is 00018 // null. These 'external' nodes are used to represent control flow that is not 00019 // represented (or analyzable) in the module. In particular, this analysis 00020 // builds one external node such that: 00021 // 1. All functions in the module without internal linkage will have edges 00022 // from this external node, indicating that they could be called by 00023 // functions outside of the module. 00024 // 2. All functions whose address is used for something more than a direct 00025 // call, for example being stored into a memory location will also have an 00026 // edge from this external node. Since they may be called by an unknown 00027 // caller later, they must be tracked as such. 00028 // 00029 // There is a second external node added for calls that leave this module. 00030 // Functions have a call edge to the external node iff: 00031 // 1. The function is external, reflecting the fact that they could call 00032 // anything without internal linkage or that has its address taken. 00033 // 2. The function contains an indirect function call. 00034 // 00035 // As an extension in the future, there may be multiple nodes with a null 00036 // function. These will be used when we can prove (through pointer analysis) 00037 // that an indirect call site can call only a specific set of functions. 00038 // 00039 // Because of these properties, the CallGraph captures a conservative superset 00040 // of all of the caller-callee relationships, which is useful for 00041 // transformations. 00042 // 00043 // The CallGraph class also attempts to figure out what the root of the 00044 // CallGraph is, which it currently does by looking for a function named 'main'. 00045 // If no function named 'main' is found, the external node is used as the entry 00046 // node, reflecting the fact that any function without internal linkage could 00047 // be called into (which is common for libraries). 00048 // 00049 //===----------------------------------------------------------------------===// 00050 00051 #ifndef LLVM_ANALYSIS_CALLGRAPH_H 00052 #define LLVM_ANALYSIS_CALLGRAPH_H 00053 00054 #include "llvm/ADT/GraphTraits.h" 00055 #include "llvm/ADT/STLExtras.h" 00056 #include "llvm/Pass.h" 00057 #include "llvm/Support/CallSite.h" 00058 00059 namespace llvm { 00060 00061 class Function; 00062 class Module; 00063 class CallGraphNode; 00064 00065 //===----------------------------------------------------------------------===// 00066 // CallGraph class definition 00067 // 00068 class CallGraph { 00069 protected: 00070 Module *Mod; // The module this call graph represents 00071 00072 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 00073 FunctionMapTy FunctionMap; // Map from a function to its node 00074 00075 public: 00076 //===--------------------------------------------------------------------- 00077 // Accessors... 00078 // 00079 typedef FunctionMapTy::iterator iterator; 00080 typedef FunctionMapTy::const_iterator const_iterator; 00081 00082 /// getModule - Return the module the call graph corresponds to. 00083 /// 00084 Module &getModule() const { return *Mod; } 00085 00086 inline iterator begin() { return FunctionMap.begin(); } 00087 inline iterator end() { return FunctionMap.end(); } 00088 inline const_iterator begin() const { return FunctionMap.begin(); } 00089 inline const_iterator end() const { return FunctionMap.end(); } 00090 00091 // Subscripting operators, return the call graph node for the provided 00092 // function 00093 inline const CallGraphNode *operator[](const Function *F) const { 00094 const_iterator I = FunctionMap.find(F); 00095 assert(I != FunctionMap.end() && "Function not in callgraph!"); 00096 return I->second; 00097 } 00098 inline CallGraphNode *operator[](const Function *F) { 00099 const_iterator I = FunctionMap.find(F); 00100 assert(I != FunctionMap.end() && "Function not in callgraph!"); 00101 return I->second; 00102 } 00103 00104 //Returns the CallGraphNode which is used to represent undetermined calls 00105 // into the callgraph. Override this if you want behavioural inheritance. 00106 virtual CallGraphNode* getExternalCallingNode() const { return 0; } 00107 00108 //Return the root/main method in the module, or some other root node, such 00109 // as the externalcallingnode. Overload these if you behavioural 00110 // inheritance. 00111 virtual CallGraphNode* getRoot() { return 0; } 00112 virtual const CallGraphNode* getRoot() const { return 0; } 00113 00114 //===--------------------------------------------------------------------- 00115 // Functions to keep a call graph up to date with a function that has been 00116 // modified. 00117 // 00118 00119 /// removeFunctionFromModule - Unlink the function from this module, returning 00120 /// it. Because this removes the function from the module, the call graph 00121 /// node is destroyed. This is only valid if the function does not call any 00122 /// other functions (ie, there are no edges in it's CGN). The easiest way to 00123 /// do this is to dropAllReferences before calling this. 00124 /// 00125 Function *removeFunctionFromModule(CallGraphNode *CGN); 00126 Function *removeFunctionFromModule(Function *F) { 00127 return removeFunctionFromModule((*this)[F]); 00128 } 00129 00130 /// changeFunction - This method changes the function associated with this 00131 /// CallGraphNode, for use by transformations that need to change the 00132 /// prototype of a Function (thus they must create a new Function and move the 00133 /// old code over). 00134 void changeFunction(Function *OldF, Function *NewF); 00135 00136 /// getOrInsertFunction - This method is identical to calling operator[], but 00137 /// it will insert a new CallGraphNode for the specified function if one does 00138 /// not already exist. 00139 CallGraphNode *getOrInsertFunction(const Function *F); 00140 00141 //===--------------------------------------------------------------------- 00142 // Pass infrastructure interface glue code... 00143 // 00144 protected: 00145 CallGraph() {} 00146 00147 public: 00148 virtual ~CallGraph() { destroy(); } 00149 00150 /// initialize - Call this method before calling other methods, 00151 /// re/initializes the state of the CallGraph. 00152 /// 00153 void initialize(Module &M); 00154 00155 virtual void print(std::ostream &o, const Module *M) const; 00156 void dump() const; 00157 00158 // stub - dummy function, just ignore it 00159 static int stub; 00160 protected: 00161 00162 // destroy - Release memory for the call graph 00163 virtual void destroy(); 00164 }; 00165 00166 //===----------------------------------------------------------------------===// 00167 // CallGraphNode class definition 00168 // 00169 class CallGraphNode { 00170 Function *F; 00171 typedef std::pair<CallSite,CallGraphNode*> CallRecord; 00172 std::vector<CallRecord> CalledFunctions; 00173 00174 CallGraphNode(const CallGraphNode &); // Do not implement 00175 public: 00176 //===--------------------------------------------------------------------- 00177 // Accessor methods... 00178 // 00179 00180 typedef std::vector<CallRecord>::iterator iterator; 00181 typedef std::vector<CallRecord>::const_iterator const_iterator; 00182 00183 // getFunction - Return the function that this call graph node represents... 00184 Function *getFunction() const { return F; } 00185 00186 inline iterator begin() { return CalledFunctions.begin(); } 00187 inline iterator end() { return CalledFunctions.end(); } 00188 inline const_iterator begin() const { return CalledFunctions.begin(); } 00189 inline const_iterator end() const { return CalledFunctions.end(); } 00190 inline unsigned size() const { return CalledFunctions.size(); } 00191 00192 // Subscripting operator - Return the i'th called function... 00193 // 00194 CallGraphNode *operator[](unsigned i) const { 00195 return CalledFunctions[i].second; 00196 } 00197 00198 /// dump - Print out this call graph node. 00199 /// 00200 void dump() const; 00201 void print(std::ostream &OS) const; 00202 00203 //===--------------------------------------------------------------------- 00204 // Methods to keep a call graph up to date with a function that has been 00205 // modified 00206 // 00207 00208 /// removeAllCalledFunctions - As the name implies, this removes all edges 00209 /// from this CallGraphNode to any functions it calls. 00210 void removeAllCalledFunctions() { 00211 CalledFunctions.clear(); 00212 } 00213 00214 /// addCalledFunction add a function to the list of functions called by this 00215 /// one. 00216 void addCalledFunction(CallSite CS, CallGraphNode *M) { 00217 CalledFunctions.push_back(std::make_pair(CS, M)); 00218 } 00219 00220 /// removeCallEdgeTo - This method removes a *single* edge to the specified 00221 /// callee function. Note that this method takes linear time, so it should be 00222 /// used sparingly. 00223 void removeCallEdgeTo(CallGraphNode *Callee); 00224 00225 /// removeAnyCallEdgeTo - This method removes any call edges from this node to 00226 /// the specified callee function. This takes more time to execute than 00227 /// removeCallEdgeTo, so it should not be used unless necessary. 00228 void removeAnyCallEdgeTo(CallGraphNode *Callee); 00229 00230 friend class CallGraph; 00231 00232 // CallGraphNode ctor - Create a node for the specified function. 00233 inline CallGraphNode(Function *f) : F(f) {} 00234 }; 00235 00236 //===----------------------------------------------------------------------===// 00237 // GraphTraits specializations for call graphs so that they can be treated as 00238 // graphs by the generic graph algorithms. 00239 // 00240 00241 // Provide graph traits for tranversing call graphs using standard graph 00242 // traversals. 00243 template <> struct GraphTraits<CallGraphNode*> { 00244 typedef CallGraphNode NodeType; 00245 00246 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy; 00247 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 00248 00249 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 00250 00251 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 00252 00253 static inline ChildIteratorType child_begin(NodeType *N) { 00254 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 00255 } 00256 static inline ChildIteratorType child_end (NodeType *N) { 00257 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 00258 } 00259 00260 static CallGraphNode *CGNDeref(CGNPairTy P) { 00261 return P.second; 00262 } 00263 00264 }; 00265 00266 template <> struct GraphTraits<const CallGraphNode*> { 00267 typedef const CallGraphNode NodeType; 00268 typedef NodeType::const_iterator ChildIteratorType; 00269 00270 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 00271 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 00272 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 00273 }; 00274 00275 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 00276 static NodeType *getEntryNode(CallGraph *CGN) { 00277 return CGN->getExternalCallingNode(); // Start at the external node! 00278 } 00279 typedef std::pair<const Function*, CallGraphNode*> PairTy; 00280 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 00281 00282 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 00283 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 00284 static nodes_iterator nodes_begin(CallGraph *CG) { 00285 return map_iterator(CG->begin(), DerefFun(CGdereference)); 00286 } 00287 static nodes_iterator nodes_end (CallGraph *CG) { 00288 return map_iterator(CG->end(), DerefFun(CGdereference)); 00289 } 00290 00291 static CallGraphNode &CGdereference(PairTy P) { 00292 return *P.second; 00293 } 00294 }; 00295 00296 template<> struct GraphTraits<const CallGraph*> : 00297 public GraphTraits<const CallGraphNode*> { 00298 static NodeType *getEntryNode(const CallGraph *CGN) { 00299 return CGN->getExternalCallingNode(); 00300 } 00301 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 00302 typedef CallGraph::const_iterator nodes_iterator; 00303 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 00304 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 00305 }; 00306 00307 } // End llvm namespace 00308 00309 // Make sure that any clients of this file link in CallGraph.cpp 00310 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 00311 00312 #endif