CallGraph.h revision b374b90e81d0ce6b5d02041ba4f7b15a945b38d8
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 /// getOrInsertFunction - This method is identical to calling operator[], but 134 /// it will insert a new CallGraphNode for the specified function if one does 135 /// not already exist. 136 CallGraphNode *getOrInsertFunction(const Function *F); 137 138 //===--------------------------------------------------------------------- 139 // Pass infrastructure interface glue code. 140 // 141protected: 142 CallGraph() {} 143 144public: 145 virtual ~CallGraph() { destroy(); } 146 147 /// initialize - Call this method before calling other methods, 148 /// re/initializes the state of the CallGraph. 149 /// 150 void initialize(Module &M); 151 152 void print(raw_ostream &o, Module *) const; 153 void dump() const; 154protected: 155 // destroy - Release memory for the call graph 156 virtual void destroy(); 157}; 158 159//===----------------------------------------------------------------------===// 160// CallGraphNode class definition 161// 162class CallGraphNode { 163 Function *F; 164 typedef std::pair<CallSite,CallGraphNode*> CallRecord; 165 std::vector<CallRecord> CalledFunctions; 166 167 /// NumReferences - This is the number of times that this CallGraphNode occurs 168 /// in the CalledFunctions array of this or other CallGraphNodes. 169 unsigned NumReferences; 170 171 CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT 172 void operator=(const CallGraphNode &); // DO NOT IMPLEMENT 173 174 void DropRef() { --NumReferences; } 175 void AddRef() { ++NumReferences; } 176public: 177 typedef std::vector<CallRecord> CalledFunctionsVector; 178 179 180 // CallGraphNode ctor - Create a node for the specified function. 181 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {} 182 183 //===--------------------------------------------------------------------- 184 // Accessor methods. 185 // 186 187 typedef std::vector<CallRecord>::iterator iterator; 188 typedef std::vector<CallRecord>::const_iterator const_iterator; 189 190 // getFunction - Return the function that this call graph node represents. 191 Function *getFunction() const { return F; } 192 193 inline iterator begin() { return CalledFunctions.begin(); } 194 inline iterator end() { return CalledFunctions.end(); } 195 inline const_iterator begin() const { return CalledFunctions.begin(); } 196 inline const_iterator end() const { return CalledFunctions.end(); } 197 inline bool empty() const { return CalledFunctions.empty(); } 198 inline unsigned size() const { return (unsigned)CalledFunctions.size(); } 199 200 /// getNumReferences - Return the number of other CallGraphNodes in this 201 /// CallGraph that reference this node in their callee list. 202 unsigned getNumReferences() const { return NumReferences; } 203 204 // Subscripting operator - Return the i'th called function. 205 // 206 CallGraphNode *operator[](unsigned i) const { 207 assert(i < CalledFunctions.size() && "Invalid index"); 208 return CalledFunctions[i].second; 209 } 210 211 /// dump - Print out this call graph node. 212 /// 213 void dump() const; 214 void print(raw_ostream &OS) const; 215 216 //===--------------------------------------------------------------------- 217 // Methods to keep a call graph up to date with a function that has been 218 // modified 219 // 220 221 /// removeAllCalledFunctions - As the name implies, this removes all edges 222 /// from this CallGraphNode to any functions it calls. 223 void removeAllCalledFunctions() { 224 while (!CalledFunctions.empty()) { 225 CalledFunctions.back().second->DropRef(); 226 CalledFunctions.pop_back(); 227 } 228 } 229 230 /// stealCalledFunctionsFrom - Move all the callee information from N to this 231 /// node. 232 void stealCalledFunctionsFrom(CallGraphNode *N) { 233 assert(CalledFunctions.empty() && 234 "Cannot steal callsite information if I already have some"); 235 std::swap(CalledFunctions, N->CalledFunctions); 236 } 237 238 239 /// addCalledFunction - Add a function to the list of functions called by this 240 /// one. 241 void addCalledFunction(CallSite CS, CallGraphNode *M) { 242 CalledFunctions.push_back(std::make_pair(CS, M)); 243 M->AddRef(); 244 } 245 246 /// removeCallEdgeFor - This method removes the edge in the node for the 247 /// specified call site. Note that this method takes linear time, so it 248 /// should be used sparingly. 249 void removeCallEdgeFor(CallSite CS); 250 251 /// removeAnyCallEdgeTo - This method removes all call edges from this node 252 /// to the specified callee function. This takes more time to execute than 253 /// removeCallEdgeTo, so it should not be used unless necessary. 254 void removeAnyCallEdgeTo(CallGraphNode *Callee); 255 256 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 257 /// from this node to the specified callee function. 258 void removeOneAbstractEdgeTo(CallGraphNode *Callee); 259 260 /// replaceCallSite - Make the edge in the node for Old CallSite be for 261 /// New CallSite instead. Note that this method takes linear time, so it 262 /// should be used sparingly. 263 void replaceCallSite(CallSite Old, CallSite New, CallGraphNode *NewCallee); 264}; 265 266//===----------------------------------------------------------------------===// 267// GraphTraits specializations for call graphs so that they can be treated as 268// graphs by the generic graph algorithms. 269// 270 271// Provide graph traits for tranversing call graphs using standard graph 272// traversals. 273template <> struct GraphTraits<CallGraphNode*> { 274 typedef CallGraphNode NodeType; 275 276 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy; 277 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 278 279 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 280 281 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 282 283 static inline ChildIteratorType child_begin(NodeType *N) { 284 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 285 } 286 static inline ChildIteratorType child_end (NodeType *N) { 287 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 288 } 289 290 static CallGraphNode *CGNDeref(CGNPairTy P) { 291 return P.second; 292 } 293 294}; 295 296template <> struct GraphTraits<const CallGraphNode*> { 297 typedef const CallGraphNode NodeType; 298 typedef NodeType::const_iterator ChildIteratorType; 299 300 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 301 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 302 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 303}; 304 305template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 306 static NodeType *getEntryNode(CallGraph *CGN) { 307 return CGN->getExternalCallingNode(); // Start at the external node! 308 } 309 typedef std::pair<const Function*, CallGraphNode*> PairTy; 310 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 311 312 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 313 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 314 static nodes_iterator nodes_begin(CallGraph *CG) { 315 return map_iterator(CG->begin(), DerefFun(CGdereference)); 316 } 317 static nodes_iterator nodes_end (CallGraph *CG) { 318 return map_iterator(CG->end(), DerefFun(CGdereference)); 319 } 320 321 static CallGraphNode &CGdereference(PairTy P) { 322 return *P.second; 323 } 324}; 325 326template<> struct GraphTraits<const CallGraph*> : 327 public GraphTraits<const CallGraphNode*> { 328 static NodeType *getEntryNode(const CallGraph *CGN) { 329 return CGN->getExternalCallingNode(); 330 } 331 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 332 typedef CallGraph::const_iterator nodes_iterator; 333 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 334 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 335}; 336 337} // End llvm namespace 338 339// Make sure that any clients of this file link in CallGraph.cpp 340FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 341 342#endif 343