CallGraph.h revision a2582da44dbe7204aac49cdaeccfd4e77ff7c408
1//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===// 2// 3// The LLVM Compiler Infrastructure 4// 5// This file is distributed under the University of Illinois Open Source 6// 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#include "llvm/System/IncludeFile.h" 59#include <map> 60 61namespace llvm { 62 63class Function; 64class Module; 65class CallGraphNode; 66 67//===----------------------------------------------------------------------===// 68// CallGraph class definition 69// 70class CallGraph { 71protected: 72 Module *Mod; // The module this call graph represents 73 74 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 75 FunctionMapTy FunctionMap; // Map from a function to its node 76 77public: 78 static char ID; // Class identification, replacement for typeinfo 79 //===--------------------------------------------------------------------- 80 // Accessors... 81 // 82 typedef FunctionMapTy::iterator iterator; 83 typedef FunctionMapTy::const_iterator const_iterator; 84 85 /// getModule - Return the module the call graph corresponds to. 86 /// 87 Module &getModule() const { return *Mod; } 88 89 inline iterator begin() { return FunctionMap.begin(); } 90 inline iterator end() { return FunctionMap.end(); } 91 inline const_iterator begin() const { return FunctionMap.begin(); } 92 inline const_iterator end() const { return FunctionMap.end(); } 93 94 // Subscripting operators, return the call graph node for the provided 95 // function 96 inline const CallGraphNode *operator[](const Function *F) const { 97 const_iterator I = FunctionMap.find(F); 98 assert(I != FunctionMap.end() && "Function not in callgraph!"); 99 return I->second; 100 } 101 inline CallGraphNode *operator[](const Function *F) { 102 const_iterator I = FunctionMap.find(F); 103 assert(I != FunctionMap.end() && "Function not in callgraph!"); 104 return I->second; 105 } 106 107 /// Returns the CallGraphNode which is used to represent undetermined calls 108 /// into the callgraph. Override this if you want behavioral inheritance. 109 virtual CallGraphNode* getExternalCallingNode() const { return 0; } 110 111 /// Return the root/main method in the module, or some other root node, such 112 /// as the externalcallingnode. Overload these if you behavioral 113 /// inheritance. 114 virtual CallGraphNode* getRoot() { return 0; } 115 virtual const CallGraphNode* getRoot() const { return 0; } 116 117 //===--------------------------------------------------------------------- 118 // Functions to keep a call graph up to date with a function that has been 119 // modified. 120 // 121 122 /// removeFunctionFromModule - Unlink the function from this module, returning 123 /// it. Because this removes the function from the module, the call graph 124 /// node is destroyed. This is only valid if the function does not call any 125 /// other functions (ie, there are no edges in it's CGN). The easiest way to 126 /// do this is to dropAllReferences before calling this. 127 /// 128 Function *removeFunctionFromModule(CallGraphNode *CGN); 129 Function *removeFunctionFromModule(Function *F) { 130 return removeFunctionFromModule((*this)[F]); 131 } 132 133 /// changeFunction - This method changes the function associated with this 134 /// CallGraphNode, for use by transformations that need to change the 135 /// prototype of a Function (thus they must create a new Function and move the 136 /// old code over). 137 void changeFunction(Function *OldF, Function *NewF); 138 139 /// getOrInsertFunction - This method is identical to calling operator[], but 140 /// it will insert a new CallGraphNode for the specified function if one does 141 /// not already exist. 142 CallGraphNode *getOrInsertFunction(const Function *F); 143 144 //===--------------------------------------------------------------------- 145 // Pass infrastructure interface glue code... 146 // 147protected: 148 CallGraph() {} 149 150public: 151 virtual ~CallGraph() { destroy(); } 152 153 /// initialize - Call this method before calling other methods, 154 /// re/initializes the state of the CallGraph. 155 /// 156 void initialize(Module &M); 157 158 virtual void print(std::ostream &o, const Module *M) const; 159 void print(std::ostream *o, const Module *M) const { if (o) print(*o, M); } 160 void dump() const; 161 162protected: 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 bool empty() const { return CalledFunctions.empty(); } 192 inline unsigned size() const { return (unsigned)CalledFunctions.size(); } 193 194 // Subscripting operator - Return the i'th called function... 195 // 196 CallGraphNode *operator[](unsigned i) const { 197 return CalledFunctions[i].second; 198 } 199 200 /// dump - Print out this call graph node. 201 /// 202 void dump() const; 203 void print(std::ostream &OS) const; 204 void print(std::ostream *OS) const { if (OS) print(*OS); } 205 206 //===--------------------------------------------------------------------- 207 // Methods to keep a call graph up to date with a function that has been 208 // modified 209 // 210 211 /// removeAllCalledFunctions - As the name implies, this removes all edges 212 /// from this CallGraphNode to any functions it calls. 213 void removeAllCalledFunctions() { 214 CalledFunctions.clear(); 215 } 216 217 /// addCalledFunction - Add a function to the list of functions called by this 218 /// one. 219 void addCalledFunction(CallSite CS, CallGraphNode *M) { 220 CalledFunctions.push_back(std::make_pair(CS, M)); 221 } 222 223 /// removeCallEdgeFor - This method removes the edge in the node for the 224 /// specified call site. Note that this method takes linear time, so it 225 /// should be used sparingly. 226 void removeCallEdgeFor(CallSite CS); 227 228 /// removeAnyCallEdgeTo - This method removes all call edges from this node 229 /// to the specified callee function. This takes more time to execute than 230 /// removeCallEdgeTo, so it should not be used unless necessary. 231 void removeAnyCallEdgeTo(CallGraphNode *Callee); 232 233 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 234 /// from this node to the specified callee function. 235 void removeOneAbstractEdgeTo(CallGraphNode *Callee); 236 237 /// replaceCallSite - Make the edge in the node for Old CallSite be for 238 /// New CallSite instead. Note that this method takes linear time, so it 239 /// should be used sparingly. 240 void replaceCallSite(CallSite Old, CallSite New); 241 242 friend class CallGraph; 243 244 // CallGraphNode ctor - Create a node for the specified function. 245 inline CallGraphNode(Function *f) : F(f) {} 246}; 247 248//===----------------------------------------------------------------------===// 249// GraphTraits specializations for call graphs so that they can be treated as 250// graphs by the generic graph algorithms. 251// 252 253// Provide graph traits for tranversing call graphs using standard graph 254// traversals. 255template <> struct GraphTraits<CallGraphNode*> { 256 typedef CallGraphNode NodeType; 257 258 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy; 259 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 260 261 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 262 263 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 264 265 static inline ChildIteratorType child_begin(NodeType *N) { 266 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 267 } 268 static inline ChildIteratorType child_end (NodeType *N) { 269 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 270 } 271 272 static CallGraphNode *CGNDeref(CGNPairTy P) { 273 return P.second; 274 } 275 276}; 277 278template <> struct GraphTraits<const CallGraphNode*> { 279 typedef const CallGraphNode NodeType; 280 typedef NodeType::const_iterator ChildIteratorType; 281 282 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 283 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 284 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 285}; 286 287template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 288 static NodeType *getEntryNode(CallGraph *CGN) { 289 return CGN->getExternalCallingNode(); // Start at the external node! 290 } 291 typedef std::pair<const Function*, CallGraphNode*> PairTy; 292 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 293 294 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 295 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 296 static nodes_iterator nodes_begin(CallGraph *CG) { 297 return map_iterator(CG->begin(), DerefFun(CGdereference)); 298 } 299 static nodes_iterator nodes_end (CallGraph *CG) { 300 return map_iterator(CG->end(), DerefFun(CGdereference)); 301 } 302 303 static CallGraphNode &CGdereference(PairTy P) { 304 return *P.second; 305 } 306}; 307 308template<> struct GraphTraits<const CallGraph*> : 309 public GraphTraits<const CallGraphNode*> { 310 static NodeType *getEntryNode(const CallGraph *CGN) { 311 return CGN->getExternalCallingNode(); 312 } 313 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 314 typedef CallGraph::const_iterator nodes_iterator; 315 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 316 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 317}; 318 319} // End llvm namespace 320 321// Make sure that any clients of this file link in CallGraph.cpp 322FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 323 324#endif 325