CallGraph.h revision ca24a695e7727da5df40a819d1144c32c8fb0110
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/Function.h" 55#include "llvm/Pass.h" 56#include "llvm/ADT/GraphTraits.h" 57#include "llvm/ADT/STLExtras.h" 58#include "llvm/Support/CallSite.h" 59#include "llvm/Support/ValueHandle.h" 60#include "llvm/System/IncludeFile.h" 61#include <map> 62 63namespace llvm { 64 65class Function; 66class Module; 67class CallGraphNode; 68 69//===----------------------------------------------------------------------===// 70// CallGraph class definition 71// 72class CallGraph { 73protected: 74 Module *Mod; // The module this call graph represents 75 76 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 77 FunctionMapTy FunctionMap; // Map from a function to its node 78 79public: 80 static char ID; // Class identification, replacement for typeinfo 81 //===--------------------------------------------------------------------- 82 // Accessors. 83 // 84 typedef FunctionMapTy::iterator iterator; 85 typedef FunctionMapTy::const_iterator const_iterator; 86 87 /// getModule - Return the module the call graph corresponds to. 88 /// 89 Module &getModule() const { return *Mod; } 90 91 inline iterator begin() { return FunctionMap.begin(); } 92 inline iterator end() { return FunctionMap.end(); } 93 inline const_iterator begin() const { return FunctionMap.begin(); } 94 inline const_iterator end() const { return FunctionMap.end(); } 95 96 // Subscripting operators, return the call graph node for the provided 97 // function 98 inline const CallGraphNode *operator[](const Function *F) const { 99 const_iterator I = FunctionMap.find(F); 100 assert(I != FunctionMap.end() && "Function not in callgraph!"); 101 return I->second; 102 } 103 inline CallGraphNode *operator[](const Function *F) { 104 const_iterator I = FunctionMap.find(F); 105 assert(I != FunctionMap.end() && "Function not in callgraph!"); 106 return I->second; 107 } 108 109 /// Returns the CallGraphNode which is used to represent undetermined calls 110 /// into the callgraph. Override this if you want behavioral inheritance. 111 virtual CallGraphNode* getExternalCallingNode() const { return 0; } 112 virtual CallGraphNode* getCallsExternalNode() const { return 0; } 113 114 /// Return the root/main method in the module, or some other root node, such 115 /// as the externalcallingnode. Overload these if you behavioral 116 /// inheritance. 117 virtual CallGraphNode* getRoot() { return 0; } 118 virtual const CallGraphNode* getRoot() const { return 0; } 119 120 //===--------------------------------------------------------------------- 121 // Functions to keep a call graph up to date with a function that has been 122 // modified. 123 // 124 125 /// removeFunctionFromModule - Unlink the function from this module, returning 126 /// it. Because this removes the function from the module, the call graph 127 /// node is destroyed. This is only valid if the function does not call any 128 /// other functions (ie, there are no edges in it's CGN). The easiest way to 129 /// do this is to dropAllReferences before calling this. 130 /// 131 Function *removeFunctionFromModule(CallGraphNode *CGN); 132 Function *removeFunctionFromModule(Function *F) { 133 return removeFunctionFromModule((*this)[F]); 134 } 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 void print(raw_ostream &o, Module *) const; 156 void dump() const; 157protected: 158 // destroy - Release memory for the call graph 159 virtual void destroy(); 160}; 161 162//===----------------------------------------------------------------------===// 163// CallGraphNode class definition. 164// 165class CallGraphNode { 166 AssertingVH<Function> F; 167 168 // CallRecord - This is a pair of the calling instruction (a call or invoke) 169 // and the callgraph node being called. 170public: 171 typedef std::pair<WeakVH, CallGraphNode*> CallRecord; 172private: 173 std::vector<CallRecord> CalledFunctions; 174 175 /// NumReferences - This is the number of times that this CallGraphNode occurs 176 /// in the CalledFunctions array of this or other CallGraphNodes. 177 unsigned NumReferences; 178 179 CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT 180 void operator=(const CallGraphNode &); // DO NOT IMPLEMENT 181 182 void DropRef() { --NumReferences; } 183 void AddRef() { ++NumReferences; } 184public: 185 typedef std::vector<CallRecord> CalledFunctionsVector; 186 187 188 // CallGraphNode ctor - Create a node for the specified function. 189 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {} 190 191 //===--------------------------------------------------------------------- 192 // Accessor methods. 193 // 194 195 typedef std::vector<CallRecord>::iterator iterator; 196 typedef std::vector<CallRecord>::const_iterator const_iterator; 197 198 // getFunction - Return the function that this call graph node represents. 199 Function *getFunction() const { return F; } 200 201 inline iterator begin() { return CalledFunctions.begin(); } 202 inline iterator end() { return CalledFunctions.end(); } 203 inline const_iterator begin() const { return CalledFunctions.begin(); } 204 inline const_iterator end() const { return CalledFunctions.end(); } 205 inline bool empty() const { return CalledFunctions.empty(); } 206 inline unsigned size() const { return (unsigned)CalledFunctions.size(); } 207 208 /// getNumReferences - Return the number of other CallGraphNodes in this 209 /// CallGraph that reference this node in their callee list. 210 unsigned getNumReferences() const { return NumReferences; } 211 212 // Subscripting operator - Return the i'th called function. 213 // 214 CallGraphNode *operator[](unsigned i) const { 215 assert(i < CalledFunctions.size() && "Invalid index"); 216 return CalledFunctions[i].second; 217 } 218 219 /// dump - Print out this call graph node. 220 /// 221 void dump() const; 222 void print(raw_ostream &OS) const; 223 224 //===--------------------------------------------------------------------- 225 // Methods to keep a call graph up to date with a function that has been 226 // modified 227 // 228 229 /// removeAllCalledFunctions - As the name implies, this removes all edges 230 /// from this CallGraphNode to any functions it calls. 231 void removeAllCalledFunctions() { 232 while (!CalledFunctions.empty()) { 233 CalledFunctions.back().second->DropRef(); 234 CalledFunctions.pop_back(); 235 } 236 } 237 238 /// stealCalledFunctionsFrom - Move all the callee information from N to this 239 /// node. 240 void stealCalledFunctionsFrom(CallGraphNode *N) { 241 assert(CalledFunctions.empty() && 242 "Cannot steal callsite information if I already have some"); 243 std::swap(CalledFunctions, N->CalledFunctions); 244 } 245 246 247 /// addCalledFunction - Add a function to the list of functions called by this 248 /// one. 249 void addCalledFunction(CallSite CS, CallGraphNode *M) { 250 CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M)); 251 M->AddRef(); 252 } 253 254 void removeCallEdge(iterator I) { 255 I->second->DropRef(); 256 *I = CalledFunctions.back(); 257 CalledFunctions.pop_back(); 258 } 259 260 261 /// removeCallEdgeFor - This method removes the edge in the node for the 262 /// specified call site. Note that this method takes linear time, so it 263 /// should be used sparingly. 264 void removeCallEdgeFor(CallSite CS); 265 266 /// removeAnyCallEdgeTo - This method removes all call edges from this node 267 /// to the specified callee function. This takes more time to execute than 268 /// removeCallEdgeTo, so it should not be used unless necessary. 269 void removeAnyCallEdgeTo(CallGraphNode *Callee); 270 271 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 272 /// from this node to the specified callee function. 273 void removeOneAbstractEdgeTo(CallGraphNode *Callee); 274 275 /// replaceCallEdge - This method replaces the edge in the node for the 276 /// specified call site with a new one. Note that this method takes linear 277 /// time, so it should be used sparingly. 278 void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode); 279 280}; 281 282//===----------------------------------------------------------------------===// 283// GraphTraits specializations for call graphs so that they can be treated as 284// graphs by the generic graph algorithms. 285// 286 287// Provide graph traits for tranversing call graphs using standard graph 288// traversals. 289template <> struct GraphTraits<CallGraphNode*> { 290 typedef CallGraphNode NodeType; 291 292 typedef CallGraphNode::CallRecord CGNPairTy; 293 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 294 295 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 296 297 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 298 299 static inline ChildIteratorType child_begin(NodeType *N) { 300 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 301 } 302 static inline ChildIteratorType child_end (NodeType *N) { 303 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 304 } 305 306 static CallGraphNode *CGNDeref(CGNPairTy P) { 307 return P.second; 308 } 309 310}; 311 312template <> struct GraphTraits<const CallGraphNode*> { 313 typedef const CallGraphNode NodeType; 314 typedef NodeType::const_iterator ChildIteratorType; 315 316 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 317 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 318 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 319}; 320 321template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 322 static NodeType *getEntryNode(CallGraph *CGN) { 323 return CGN->getExternalCallingNode(); // Start at the external node! 324 } 325 typedef std::pair<const Function*, CallGraphNode*> PairTy; 326 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 327 328 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 329 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 330 static nodes_iterator nodes_begin(CallGraph *CG) { 331 return map_iterator(CG->begin(), DerefFun(CGdereference)); 332 } 333 static nodes_iterator nodes_end (CallGraph *CG) { 334 return map_iterator(CG->end(), DerefFun(CGdereference)); 335 } 336 337 static CallGraphNode &CGdereference(PairTy P) { 338 return *P.second; 339 } 340}; 341 342template<> struct GraphTraits<const CallGraph*> : 343 public GraphTraits<const CallGraphNode*> { 344 static NodeType *getEntryNode(const CallGraph *CGN) { 345 return CGN->getExternalCallingNode(); 346 } 347 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 348 typedef CallGraph::const_iterator nodes_iterator; 349 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 350 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 351}; 352 353} // End llvm namespace 354 355// Make sure that any clients of this file link in CallGraph.cpp 356FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 357 358#endif 359