CallGraph.h revision 5c7e326585f3a543388ba871c3425f7664cd9143
1//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file was developed by the LLVM research group and is distributed under 6// the University of Illinois Open Source License. See LICENSE.TXT for details. 7// 8//===----------------------------------------------------------------------===// 9// 10// This interface is used to build and manipulate a call graph, which is a very 11// useful tool for interprocedural optimization. 12// 13// Every function in a module is represented as a node in the call graph. The 14// callgraph node keeps track of which functions the are called by the function 15// corresponding to the node. 16// 17// A call graph may contain nodes where the function that they correspond to is 18// null. These 'external' nodes are used to represent control flow that is not 19// represented (or analyzable) in the module. In particular, this analysis 20// builds one external node such that: 21// 1. All functions in the module without internal linkage will have edges 22// from this external node, indicating that they could be called by 23// functions outside of the module. 24// 2. All functions whose address is used for something more than a direct 25// call, for example being stored into a memory location will also have an 26// edge from this external node. Since they may be called by an unknown 27// caller later, they must be tracked as such. 28// 29// There is a second external node added for calls that leave this module. 30// Functions have a call edge to the external node iff: 31// 1. The function is external, reflecting the fact that they could call 32// anything without internal linkage or that has its address taken. 33// 2. The function contains an indirect function call. 34// 35// As an extension in the future, there may be multiple nodes with a null 36// function. These will be used when we can prove (through pointer analysis) 37// that an indirect call site can call only a specific set of functions. 38// 39// Because of these properties, the CallGraph captures a conservative superset 40// of all of the caller-callee relationships, which is useful for 41// transformations. 42// 43// The CallGraph class also attempts to figure out what the root of the 44// CallGraph is, which it currently does by looking for a function named 'main'. 45// If no function named 'main' is found, the external node is used as the entry 46// node, reflecting the fact that any function without internal linkage could 47// be called into (which is common for libraries). 48// 49//===----------------------------------------------------------------------===// 50 51#ifndef LLVM_ANALYSIS_CALLGRAPH_H 52#define LLVM_ANALYSIS_CALLGRAPH_H 53 54#include "llvm/ADT/GraphTraits.h" 55#include "llvm/ADT/STLExtras.h" 56#include "llvm/Pass.h" 57#include "llvm/Support/CallSite.h" 58 59namespace llvm { 60 61class Function; 62class Module; 63class CallGraphNode; 64 65//===----------------------------------------------------------------------===// 66// CallGraph class definition 67// 68class CallGraph { 69protected: 70 Module *Mod; // The module this call graph represents 71 72 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 73 FunctionMapTy FunctionMap; // Map from a function to its node 74 75public: 76 //===--------------------------------------------------------------------- 77 // Accessors... 78 // 79 typedef FunctionMapTy::iterator iterator; 80 typedef FunctionMapTy::const_iterator const_iterator; 81 82 /// getModule - Return the module the call graph corresponds to. 83 /// 84 Module &getModule() const { return *Mod; } 85 86 inline iterator begin() { return FunctionMap.begin(); } 87 inline iterator end() { return FunctionMap.end(); } 88 inline const_iterator begin() const { return FunctionMap.begin(); } 89 inline const_iterator end() const { return FunctionMap.end(); } 90 91 // Subscripting operators, return the call graph node for the provided 92 // function 93 inline const CallGraphNode *operator[](const Function *F) const { 94 const_iterator I = FunctionMap.find(F); 95 assert(I != FunctionMap.end() && "Function not in callgraph!"); 96 return I->second; 97 } 98 inline CallGraphNode *operator[](const Function *F) { 99 const_iterator I = FunctionMap.find(F); 100 assert(I != FunctionMap.end() && "Function not in callgraph!"); 101 return I->second; 102 } 103 104 //Returns the CallGraphNode which is used to represent undetermined calls 105 // into the callgraph. Override this if you want behavioural inheritance. 106 virtual CallGraphNode* getExternalCallingNode() const { return 0; } 107 108 //Return the root/main method in the module, or some other root node, such 109 // as the externalcallingnode. Overload these if you behavioural 110 // inheritance. 111 virtual CallGraphNode* getRoot() { return 0; } 112 virtual const CallGraphNode* getRoot() const { return 0; } 113 114 //===--------------------------------------------------------------------- 115 // Functions to keep a call graph up to date with a function that has been 116 // modified. 117 // 118 119 /// removeFunctionFromModule - Unlink the function from this module, returning 120 /// it. Because this removes the function from the module, the call graph 121 /// node is destroyed. This is only valid if the function does not call any 122 /// other functions (ie, there are no edges in it's CGN). The easiest way to 123 /// do this is to dropAllReferences before calling this. 124 /// 125 Function *removeFunctionFromModule(CallGraphNode *CGN); 126 Function *removeFunctionFromModule(Function *F) { 127 return removeFunctionFromModule((*this)[F]); 128 } 129 130 /// changeFunction - This method changes the function associated with this 131 /// CallGraphNode, for use by transformations that need to change the 132 /// prototype of a Function (thus they must create a new Function and move the 133 /// old code over). 134 void changeFunction(Function *OldF, Function *NewF); 135 136 /// getOrInsertFunction - This method is identical to calling operator[], but 137 /// it will insert a new CallGraphNode for the specified function if one does 138 /// not already exist. 139 CallGraphNode *getOrInsertFunction(const Function *F); 140 141 //===--------------------------------------------------------------------- 142 // Pass infrastructure interface glue code... 143 // 144protected: 145 CallGraph() {} 146 147public: 148 virtual ~CallGraph() { destroy(); } 149 150 /// initialize - Call this method before calling other methods, 151 /// re/initializes the state of the CallGraph. 152 /// 153 void initialize(Module &M); 154 155 virtual void print(std::ostream &o, const Module *M) const; 156 void print(std::ostream *o, const Module *M) const { if (o) print(*o, M); } 157 void dump() const; 158 159 // stub - dummy function, just ignore it 160 static int stub; 161protected: 162 163 // destroy - Release memory for the call graph 164 virtual void destroy(); 165}; 166 167//===----------------------------------------------------------------------===// 168// CallGraphNode class definition 169// 170class CallGraphNode { 171 Function *F; 172 typedef std::pair<CallSite,CallGraphNode*> CallRecord; 173 std::vector<CallRecord> CalledFunctions; 174 175 CallGraphNode(const CallGraphNode &); // Do not implement 176public: 177 //===--------------------------------------------------------------------- 178 // Accessor methods... 179 // 180 181 typedef std::vector<CallRecord>::iterator iterator; 182 typedef std::vector<CallRecord>::const_iterator const_iterator; 183 184 // getFunction - Return the function that this call graph node represents... 185 Function *getFunction() const { return F; } 186 187 inline iterator begin() { return CalledFunctions.begin(); } 188 inline iterator end() { return CalledFunctions.end(); } 189 inline const_iterator begin() const { return CalledFunctions.begin(); } 190 inline const_iterator end() const { return CalledFunctions.end(); } 191 inline unsigned size() const { return CalledFunctions.size(); } 192 193 // Subscripting operator - Return the i'th called function... 194 // 195 CallGraphNode *operator[](unsigned i) const { 196 return CalledFunctions[i].second; 197 } 198 199 /// dump - Print out this call graph node. 200 /// 201 void dump() const; 202 void print(std::ostream &OS) const; 203 void print(std::ostream *OS) const { if (OS) print(*OS); } 204 205 //===--------------------------------------------------------------------- 206 // Methods to keep a call graph up to date with a function that has been 207 // modified 208 // 209 210 /// removeAllCalledFunctions - As the name implies, this removes all edges 211 /// from this CallGraphNode to any functions it calls. 212 void removeAllCalledFunctions() { 213 CalledFunctions.clear(); 214 } 215 216 /// addCalledFunction add a function to the list of functions called by this 217 /// one. 218 void addCalledFunction(CallSite CS, CallGraphNode *M) { 219 CalledFunctions.push_back(std::make_pair(CS, M)); 220 } 221 222 /// removeCallEdgeTo - This method removes a *single* edge to the specified 223 /// callee function. Note that this method takes linear time, so it should be 224 /// used sparingly. 225 void removeCallEdgeTo(CallGraphNode *Callee); 226 227 /// removeAnyCallEdgeTo - This method removes any call edges from this node to 228 /// the specified callee function. This takes more time to execute than 229 /// removeCallEdgeTo, so it should not be used unless necessary. 230 void removeAnyCallEdgeTo(CallGraphNode *Callee); 231 232 friend class CallGraph; 233 234 // CallGraphNode ctor - Create a node for the specified function. 235 inline CallGraphNode(Function *f) : F(f) {} 236}; 237 238//===----------------------------------------------------------------------===// 239// GraphTraits specializations for call graphs so that they can be treated as 240// graphs by the generic graph algorithms. 241// 242 243// Provide graph traits for tranversing call graphs using standard graph 244// traversals. 245template <> struct GraphTraits<CallGraphNode*> { 246 typedef CallGraphNode NodeType; 247 248 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy; 249 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 250 251 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 252 253 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 254 255 static inline ChildIteratorType child_begin(NodeType *N) { 256 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 257 } 258 static inline ChildIteratorType child_end (NodeType *N) { 259 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 260 } 261 262 static CallGraphNode *CGNDeref(CGNPairTy P) { 263 return P.second; 264 } 265 266}; 267 268template <> struct GraphTraits<const CallGraphNode*> { 269 typedef const CallGraphNode NodeType; 270 typedef NodeType::const_iterator ChildIteratorType; 271 272 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 273 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 274 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 275}; 276 277template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 278 static NodeType *getEntryNode(CallGraph *CGN) { 279 return CGN->getExternalCallingNode(); // Start at the external node! 280 } 281 typedef std::pair<const Function*, CallGraphNode*> PairTy; 282 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 283 284 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 285 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 286 static nodes_iterator nodes_begin(CallGraph *CG) { 287 return map_iterator(CG->begin(), DerefFun(CGdereference)); 288 } 289 static nodes_iterator nodes_end (CallGraph *CG) { 290 return map_iterator(CG->end(), DerefFun(CGdereference)); 291 } 292 293 static CallGraphNode &CGdereference(PairTy P) { 294 return *P.second; 295 } 296}; 297 298template<> struct GraphTraits<const CallGraph*> : 299 public GraphTraits<const CallGraphNode*> { 300 static NodeType *getEntryNode(const CallGraph *CGN) { 301 return CGN->getExternalCallingNode(); 302 } 303 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 304 typedef CallGraph::const_iterator nodes_iterator; 305 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 306 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 307}; 308 309} // End llvm namespace 310 311// Make sure that any clients of this file link in CallGraph.cpp 312FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 313 314#endif 315