CallGraph.h revision af8a42445c99d2d733caf1f9ef3e3b53827613d5
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 "Support/GraphTraits.h" 55#include "Support/STLExtras.h" 56#include "llvm/Pass.h" 57 58namespace llvm { 59 60class Function; 61class Module; 62class CallGraphNode; 63 64//===----------------------------------------------------------------------===// 65// CallGraph class definition 66// 67class CallGraph : public Pass { 68 Module *Mod; // The module this call graph represents 69 70 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy; 71 FunctionMapTy FunctionMap; // Map from a function to its node 72 73 // Root is root of the call graph, or the external node if a 'main' function 74 // couldn't be found. 75 // 76 CallGraphNode *Root; 77 78 // ExternalCallingNode - This node has edges to all external functions and 79 // those internal functions that have their address taken. 80 CallGraphNode *ExternalCallingNode; 81 82 // CallsExternalNode - This node has edges to it from all functions making 83 // indirect calls or calling an external function. 84 CallGraphNode *CallsExternalNode; 85 86public: 87 //===--------------------------------------------------------------------- 88 // Accessors... 89 // 90 typedef FunctionMapTy::iterator iterator; 91 typedef FunctionMapTy::const_iterator const_iterator; 92 93 CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; } 94 CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; } 95 96 // getRoot - Return the root of the call graph, which is either main, or if 97 // main cannot be found, the external node. 98 // 99 CallGraphNode *getRoot() { return Root; } 100 const CallGraphNode *getRoot() const { return Root; } 101 102 /// getModule - Return the module the call graph corresponds to. 103 /// 104 Module &getModule() const { return *Mod; } 105 106 inline iterator begin() { return FunctionMap.begin(); } 107 inline iterator end() { return FunctionMap.end(); } 108 inline const_iterator begin() const { return FunctionMap.begin(); } 109 inline const_iterator end() const { return FunctionMap.end(); } 110 111 112 // Subscripting operators, return the call graph node for the provided 113 // function 114 inline const CallGraphNode *operator[](const Function *F) const { 115 const_iterator I = FunctionMap.find(F); 116 assert(I != FunctionMap.end() && "Function not in callgraph!"); 117 return I->second; 118 } 119 inline CallGraphNode *operator[](const Function *F) { 120 const_iterator I = FunctionMap.find(F); 121 assert(I != FunctionMap.end() && "Function not in callgraph!"); 122 return I->second; 123 } 124 125 //===--------------------------------------------------------------------- 126 // Functions to keep a call graph up to date with a function that has been 127 // modified 128 // 129 void addFunctionToModule(Function *F); 130 131 132 // removeFunctionFromModule - Unlink the function from this module, returning 133 // it. Because this removes the function from the module, the call graph node 134 // is destroyed. This is only valid if the function does not call any other 135 // functions (ie, there are no edges in it's CGN). The easiest way to do this 136 // is to dropAllReferences before calling this. 137 // 138 Function *removeFunctionFromModule(CallGraphNode *CGN); 139 Function *removeFunctionFromModule(Function *F) { 140 return removeFunctionFromModule((*this)[F]); 141 } 142 143 144 //===--------------------------------------------------------------------- 145 // Pass infrastructure interface glue code... 146 // 147 CallGraph() : Root(0), CallsExternalNode(0) {} 148 ~CallGraph() { destroy(); } 149 150 // run - Compute the call graph for the specified module. 151 virtual bool run(Module &M); 152 153 // getAnalysisUsage - This obviously provides a call graph 154 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 155 AU.setPreservesAll(); 156 } 157 158 // releaseMemory - Data structures can be large, so free memory aggressively. 159 virtual void releaseMemory() { 160 destroy(); 161 } 162 163 /// Print the types found in the module. If the optional Module parameter is 164 /// passed in, then the types are printed symbolically if possible, using the 165 /// symbol table from the module. 166 /// 167 void print(std::ostream &o, const Module *M) const; 168 169 /// dump - Print out this call graph. 170 /// 171 void dump() const; 172 173 // stub - dummy function, just ignore it 174 static void stub(); 175private: 176 //===--------------------------------------------------------------------- 177 // Implementation of CallGraph construction 178 // 179 180 // getNodeFor - Return the node for the specified function or create one if it 181 // does not already exist. 182 // 183 CallGraphNode *getNodeFor(Function *F); 184 185 // addToCallGraph - Add a function to the call graph, and link the node to all 186 // of the functions that it calls. 187 // 188 void addToCallGraph(Function *F); 189 190 // destroy - Release memory for the call graph 191 void destroy(); 192}; 193 194 195//===----------------------------------------------------------------------===// 196// CallGraphNode class definition 197// 198class CallGraphNode { 199 Function *F; 200 std::vector<CallGraphNode*> CalledFunctions; 201 202 CallGraphNode(const CallGraphNode &); // Do not implement 203public: 204 //===--------------------------------------------------------------------- 205 // Accessor methods... 206 // 207 208 typedef std::vector<CallGraphNode*>::iterator iterator; 209 typedef std::vector<CallGraphNode*>::const_iterator const_iterator; 210 211 // getFunction - Return the function that this call graph node represents... 212 Function *getFunction() const { return F; } 213 214 inline iterator begin() { return CalledFunctions.begin(); } 215 inline iterator end() { return CalledFunctions.end(); } 216 inline const_iterator begin() const { return CalledFunctions.begin(); } 217 inline const_iterator end() const { return CalledFunctions.end(); } 218 inline unsigned size() const { return CalledFunctions.size(); } 219 220 // Subscripting operator - Return the i'th called function... 221 // 222 CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];} 223 224 /// dump - Print out this call graph node. 225 /// 226 void dump() const; 227 void print(std::ostream &OS) const; 228 229 //===--------------------------------------------------------------------- 230 // Methods to keep a call graph up to date with a function that has been 231 // modified 232 // 233 234 void removeAllCalledFunctions() { 235 CalledFunctions.clear(); 236 } 237 238 // addCalledFunction add a function to the list of functions called by this 239 // one 240 void addCalledFunction(CallGraphNode *M) { 241 CalledFunctions.push_back(M); 242 } 243 244 void removeCallEdgeTo(CallGraphNode *Callee); 245 246private: // Stuff to construct the node, used by CallGraph 247 friend class CallGraph; 248 249 // CallGraphNode ctor - Create a node for the specified function... 250 inline CallGraphNode(Function *f) : F(f) {} 251}; 252 253 254 255//===----------------------------------------------------------------------===// 256// GraphTraits specializations for call graphs so that they can be treated as 257// graphs by the generic graph algorithms... 258// 259 260// Provide graph traits for tranversing call graphs using standard graph 261// traversals. 262template <> struct GraphTraits<CallGraphNode*> { 263 typedef CallGraphNode NodeType; 264 typedef NodeType::iterator ChildIteratorType; 265 266 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; } 267 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 268 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 269}; 270 271template <> struct GraphTraits<const CallGraphNode*> { 272 typedef const CallGraphNode NodeType; 273 typedef NodeType::const_iterator ChildIteratorType; 274 275 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; } 276 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();} 277 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); } 278}; 279 280template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> { 281 static NodeType *getEntryNode(CallGraph *CGN) { 282 return CGN->getExternalCallingNode(); // Start at the external node! 283 } 284 typedef std::pair<const Function*, CallGraphNode*> PairTy; 285 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun; 286 287 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 288 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator; 289 static nodes_iterator nodes_begin(CallGraph *CG) { 290 return map_iterator(CG->begin(), DerefFun(CGdereference)); 291 } 292 static nodes_iterator nodes_end (CallGraph *CG) { 293 return map_iterator(CG->end(), DerefFun(CGdereference)); 294 } 295 296 static CallGraphNode &CGdereference (std::pair<const Function*, 297 CallGraphNode*> P) { 298 return *P.second; 299 } 300}; 301template<> struct GraphTraits<const CallGraph*> : 302 public GraphTraits<const CallGraphNode*> { 303 static NodeType *getEntryNode(const CallGraph *CGN) { 304 return CGN->getExternalCallingNode(); 305 } 306 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph 307 typedef CallGraph::const_iterator nodes_iterator; 308 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); } 309 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); } 310}; 311 312// Make sure that any clients of this file link in PostDominators.cpp 313static IncludeFile 314CALLGRAPH_INCLUDE_FILE((void*)&CallGraph::stub); 315 316} // End llvm namespace 317 318#endif 319