CallGraph.h revision a541b0fde2ab6b8b037edf113d42da41a2c5aae9
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/Support/ValueHandle.h" 59#include "llvm/System/IncludeFile.h" 60#include <map> 61 62namespace llvm { 63 64class Function; 65class Module; 66class CallGraphNode; 67 68//===----------------------------------------------------------------------===// 69// CallGraph class definition 70// 71class CallGraph { 72protected: 73 Module *Mod; // The module this call graph represents 74 75 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 76 FunctionMapTy FunctionMap; // Map from a function to its node 77 78public: 79 static char ID; // Class identification, replacement for typeinfo 80 //===--------------------------------------------------------------------- 81 // Accessors. 82 // 83 typedef FunctionMapTy::iterator iterator; 84 typedef FunctionMapTy::const_iterator const_iterator; 85 86 /// getModule - Return the module the call graph corresponds to. 87 /// 88 Module &getModule() const { return *Mod; } 89 90 inline iterator begin() { return FunctionMap.begin(); } 91 inline iterator end() { return FunctionMap.end(); } 92 inline const_iterator begin() const { return FunctionMap.begin(); } 93 inline const_iterator end() const { return FunctionMap.end(); } 94 95 // Subscripting operators, return the call graph node for the provided 96 // function 97 inline const CallGraphNode *operator[](const Function *F) const { 98 const_iterator I = FunctionMap.find(F); 99 assert(I != FunctionMap.end() && "Function not in callgraph!"); 100 return I->second; 101 } 102 inline CallGraphNode *operator[](const Function *F) { 103 const_iterator I = FunctionMap.find(F); 104 assert(I != FunctionMap.end() && "Function not in callgraph!"); 105 return I->second; 106 } 107 108 /// Returns the CallGraphNode which is used to represent undetermined calls 109 /// into the callgraph. Override this if you want behavioral inheritance. 110 virtual CallGraphNode* getExternalCallingNode() const { return 0; } 111 virtual CallGraphNode* getCallsExternalNode() const { return 0; } 112 113 /// Return the root/main method in the module, or some other root node, such 114 /// as the externalcallingnode. Overload these if you behavioral 115 /// inheritance. 116 virtual CallGraphNode* getRoot() { return 0; } 117 virtual const CallGraphNode* getRoot() const { return 0; } 118 119 //===--------------------------------------------------------------------- 120 // Functions to keep a call graph up to date with a function that has been 121 // modified. 122 // 123 124 /// removeFunctionFromModule - Unlink the function from this module, returning 125 /// it. Because this removes the function from the module, the call graph 126 /// node is destroyed. This is only valid if the function does not call any 127 /// other functions (ie, there are no edges in it's CGN). The easiest way to 128 /// do this is to dropAllReferences before calling this. 129 /// 130 Function *removeFunctionFromModule(CallGraphNode *CGN); 131 Function *removeFunctionFromModule(Function *F) { 132 return removeFunctionFromModule((*this)[F]); 133 } 134 135 /// getOrInsertFunction - This method is identical to calling operator[], but 136 /// it will insert a new CallGraphNode for the specified function if one does 137 /// not already exist. 138 CallGraphNode *getOrInsertFunction(const Function *F); 139 140 //===--------------------------------------------------------------------- 141 // Pass infrastructure interface glue code. 142 // 143protected: 144 CallGraph() {} 145 146public: 147 virtual ~CallGraph() { destroy(); } 148 149 /// initialize - Call this method before calling other methods, 150 /// re/initializes the state of the CallGraph. 151 /// 152 void initialize(Module &M); 153 154 void print(raw_ostream &o, Module *) const; 155 void dump() const; 156protected: 157 // destroy - Release memory for the call graph 158 virtual void destroy(); 159}; 160 161//===----------------------------------------------------------------------===// 162// CallGraphNode class definition. 163// 164class CallGraphNode { 165 AssertingVH<Function> F; 166 167 // CallRecord - This is a pair of the calling instruction (a call or invoke) 168 // and the callgraph node being called. 169public: 170 typedef std::pair<WeakVH, CallGraphNode*> CallRecord; 171private: 172 std::vector<CallRecord> CalledFunctions; 173 174 /// NumReferences - This is the number of times that this CallGraphNode occurs 175 /// in the CalledFunctions array of this or other CallGraphNodes. 176 unsigned NumReferences; 177 178 CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT 179 void operator=(const CallGraphNode &); // DO NOT IMPLEMENT 180 181 void DropRef() { --NumReferences; } 182 void AddRef() { ++NumReferences; } 183public: 184 typedef std::vector<CallRecord> CalledFunctionsVector; 185 186 187 // CallGraphNode ctor - Create a node for the specified function. 188 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {} 189 190 //===--------------------------------------------------------------------- 191 // Accessor methods. 192 // 193 194 typedef std::vector<CallRecord>::iterator iterator; 195 typedef std::vector<CallRecord>::const_iterator const_iterator; 196 197 // getFunction - Return the function that this call graph node represents. 198 Function *getFunction() const { return F; } 199 200 inline iterator begin() { return CalledFunctions.begin(); } 201 inline iterator end() { return CalledFunctions.end(); } 202 inline const_iterator begin() const { return CalledFunctions.begin(); } 203 inline const_iterator end() const { return CalledFunctions.end(); } 204 inline bool empty() const { return CalledFunctions.empty(); } 205 inline unsigned size() const { return (unsigned)CalledFunctions.size(); } 206 207 /// getNumReferences - Return the number of other CallGraphNodes in this 208 /// CallGraph that reference this node in their callee list. 209 unsigned getNumReferences() const { return NumReferences; } 210 211 // Subscripting operator - Return the i'th called function. 212 // 213 CallGraphNode *operator[](unsigned i) const { 214 assert(i < CalledFunctions.size() && "Invalid index"); 215 return CalledFunctions[i].second; 216 } 217 218 /// dump - Print out this call graph node. 219 /// 220 void dump() const; 221 void print(raw_ostream &OS) const; 222 223 //===--------------------------------------------------------------------- 224 // Methods to keep a call graph up to date with a function that has been 225 // modified 226 // 227 228 /// removeAllCalledFunctions - As the name implies, this removes all edges 229 /// from this CallGraphNode to any functions it calls. 230 void removeAllCalledFunctions() { 231 while (!CalledFunctions.empty()) { 232 CalledFunctions.back().second->DropRef(); 233 CalledFunctions.pop_back(); 234 } 235 } 236 237 /// stealCalledFunctionsFrom - Move all the callee information from N to this 238 /// node. 239 void stealCalledFunctionsFrom(CallGraphNode *N) { 240 assert(CalledFunctions.empty() && 241 "Cannot steal callsite information if I already have some"); 242 std::swap(CalledFunctions, N->CalledFunctions); 243 } 244 245 246 /// addCalledFunction - Add a function to the list of functions called by this 247 /// one. 248 void addCalledFunction(CallSite CS, CallGraphNode *M) { 249 CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M)); 250 M->AddRef(); 251 } 252 253 void removeCallEdge(iterator I) { 254 I->second->DropRef(); 255 *I = CalledFunctions.back(); 256 CalledFunctions.pop_back(); 257 } 258 259 260 /// removeCallEdgeFor - This method removes the edge in the node for the 261 /// specified call site. Note that this method takes linear time, so it 262 /// should be used sparingly. 263 void removeCallEdgeFor(CallSite CS); 264 265 /// removeAnyCallEdgeTo - This method removes all call edges from this node 266 /// to the specified callee function. This takes more time to execute than 267 /// removeCallEdgeTo, so it should not be used unless necessary. 268 void removeAnyCallEdgeTo(CallGraphNode *Callee); 269 270 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 271 /// from this node to the specified callee function. 272 void removeOneAbstractEdgeTo(CallGraphNode *Callee); 273 274 /// replaceCallSite - Make the edge in the node for Old CallSite be for 275 /// New CallSite instead. Note that this method takes linear time, so it 276 /// should be used sparingly. 277 void replaceCallSite(CallSite Old, CallSite New, CallGraphNode *NewCallee); 278}; 279 280//===----------------------------------------------------------------------===// 281// GraphTraits specializations for call graphs so that they can be treated as 282// graphs by the generic graph algorithms. 283// 284 285// Provide graph traits for tranversing call graphs using standard graph 286// traversals. 287template <> struct GraphTraits<CallGraphNode*> { 288 typedef CallGraphNode NodeType; 289 290 typedef CallGraphNode::CallRecord CGNPairTy; 291 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun; 292 293 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 294 295 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType; 296 297 static inline ChildIteratorType child_begin(NodeType *N) { 298 return map_iterator(N->begin(), CGNDerefFun(CGNDeref)); 299 } 300 static inline ChildIteratorType child_end (NodeType *N) { 301 return map_iterator(N->end(), CGNDerefFun(CGNDeref)); 302 } 303 304 static CallGraphNode *CGNDeref(CGNPairTy P) { 305 return P.second; 306 } 307 308}; 309 310template <> struct GraphTraits<const CallGraphNode*> { 311 typedef const CallGraphNode NodeType; 312 typedef NodeType::const_iterator ChildIteratorType; 313 314 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 315 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 316 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 317}; 318 319template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 320 static NodeType *getEntryNode(CallGraph *CGN) { 321 return CGN->getExternalCallingNode(); // Start at the external node! 322 } 323 typedef std::pair<const Function*, CallGraphNode*> PairTy; 324 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 325 326 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 327 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 328 static nodes_iterator nodes_begin(CallGraph *CG) { 329 return map_iterator(CG->begin(), DerefFun(CGdereference)); 330 } 331 static nodes_iterator nodes_end (CallGraph *CG) { 332 return map_iterator(CG->end(), DerefFun(CGdereference)); 333 } 334 335 static CallGraphNode &CGdereference(PairTy P) { 336 return *P.second; 337 } 338}; 339 340template<> struct GraphTraits<const CallGraph*> : 341 public GraphTraits<const CallGraphNode*> { 342 static NodeType *getEntryNode(const CallGraph *CGN) { 343 return CGN->getExternalCallingNode(); 344 } 345 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 346 typedef CallGraph::const_iterator nodes_iterator; 347 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 348 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 349}; 350 351} // End llvm namespace 352 353// Make sure that any clients of this file link in CallGraph.cpp 354FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph) 355 356#endif 357