CallGraph.cpp revision 212904
1//===- CallGraph.cpp - Build a Module's call graph ------------------------===// 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 file implements the CallGraph class and provides the BasicCallGraph 11// default implementation. 12// 13//===----------------------------------------------------------------------===// 14 15#include "llvm/Analysis/CallGraph.h" 16#include "llvm/Module.h" 17#include "llvm/Instructions.h" 18#include "llvm/IntrinsicInst.h" 19#include "llvm/Support/CallSite.h" 20#include "llvm/Support/Debug.h" 21#include "llvm/Support/raw_ostream.h" 22using namespace llvm; 23 24namespace { 25 26//===----------------------------------------------------------------------===// 27// BasicCallGraph class definition 28// 29class BasicCallGraph : public ModulePass, public CallGraph { 30 // Root is root of the call graph, or the external node if a 'main' function 31 // couldn't be found. 32 // 33 CallGraphNode *Root; 34 35 // ExternalCallingNode - This node has edges to all external functions and 36 // those internal functions that have their address taken. 37 CallGraphNode *ExternalCallingNode; 38 39 // CallsExternalNode - This node has edges to it from all functions making 40 // indirect calls or calling an external function. 41 CallGraphNode *CallsExternalNode; 42 43public: 44 static char ID; // Class identification, replacement for typeinfo 45 BasicCallGraph() : ModulePass(ID), Root(0), 46 ExternalCallingNode(0), CallsExternalNode(0) {} 47 48 // runOnModule - Compute the call graph for the specified module. 49 virtual bool runOnModule(Module &M) { 50 CallGraph::initialize(M); 51 52 ExternalCallingNode = getOrInsertFunction(0); 53 CallsExternalNode = new CallGraphNode(0); 54 Root = 0; 55 56 // Add every function to the call graph. 57 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 58 addToCallGraph(I); 59 60 // If we didn't find a main function, use the external call graph node 61 if (Root == 0) Root = ExternalCallingNode; 62 63 return false; 64 } 65 66 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 67 AU.setPreservesAll(); 68 } 69 70 virtual void print(raw_ostream &OS, const Module *) const { 71 OS << "CallGraph Root is: "; 72 if (Function *F = getRoot()->getFunction()) 73 OS << F->getName() << "\n"; 74 else { 75 OS << "<<null function: 0x" << getRoot() << ">>\n"; 76 } 77 78 CallGraph::print(OS, 0); 79 } 80 81 virtual void releaseMemory() { 82 destroy(); 83 } 84 85 /// getAdjustedAnalysisPointer - This method is used when a pass implements 86 /// an analysis interface through multiple inheritance. If needed, it should 87 /// override this to adjust the this pointer as needed for the specified pass 88 /// info. 89 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) { 90 if (PI == &CallGraph::ID) 91 return (CallGraph*)this; 92 return this; 93 } 94 95 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; } 96 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; } 97 98 // getRoot - Return the root of the call graph, which is either main, or if 99 // main cannot be found, the external node. 100 // 101 CallGraphNode *getRoot() { return Root; } 102 const CallGraphNode *getRoot() const { return Root; } 103 104private: 105 //===--------------------------------------------------------------------- 106 // Implementation of CallGraph construction 107 // 108 109 // addToCallGraph - Add a function to the call graph, and link the node to all 110 // of the functions that it calls. 111 // 112 void addToCallGraph(Function *F) { 113 CallGraphNode *Node = getOrInsertFunction(F); 114 115 // If this function has external linkage, anything could call it. 116 if (!F->hasLocalLinkage()) { 117 ExternalCallingNode->addCalledFunction(CallSite(), Node); 118 119 // Found the entry point? 120 if (F->getName() == "main") { 121 if (Root) // Found multiple external mains? Don't pick one. 122 Root = ExternalCallingNode; 123 else 124 Root = Node; // Found a main, keep track of it! 125 } 126 } 127 128 // Loop over all of the users of the function, looking for non-call uses. 129 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){ 130 User *U = *I; 131 if ((!isa<CallInst>(U) && !isa<InvokeInst>(U)) 132 || !CallSite(cast<Instruction>(U)).isCallee(I)) { 133 // Not a call, or being used as a parameter rather than as the callee. 134 ExternalCallingNode->addCalledFunction(CallSite(), Node); 135 break; 136 } 137 } 138 139 // If this function is not defined in this translation unit, it could call 140 // anything. 141 if (F->isDeclaration() && !F->isIntrinsic()) 142 Node->addCalledFunction(CallSite(), CallsExternalNode); 143 144 // Look for calls by this function. 145 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB) 146 for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); 147 II != IE; ++II) { 148 CallSite CS(cast<Value>(II)); 149 if (CS && !isa<DbgInfoIntrinsic>(II)) { 150 const Function *Callee = CS.getCalledFunction(); 151 if (Callee) 152 Node->addCalledFunction(CS, getOrInsertFunction(Callee)); 153 else 154 Node->addCalledFunction(CS, CallsExternalNode); 155 } 156 } 157 } 158 159 // 160 // destroy - Release memory for the call graph 161 virtual void destroy() { 162 /// CallsExternalNode is not in the function map, delete it explicitly. 163 if (CallsExternalNode) { 164 CallsExternalNode->allReferencesDropped(); 165 delete CallsExternalNode; 166 CallsExternalNode = 0; 167 } 168 CallGraph::destroy(); 169 } 170}; 171 172} //End anonymous namespace 173 174static RegisterAnalysisGroup<CallGraph> X("Call Graph"); 175INITIALIZE_AG_PASS(BasicCallGraph, CallGraph, "basiccg", 176 "Basic CallGraph Construction", false, true, true); 177 178char CallGraph::ID = 0; 179char BasicCallGraph::ID = 0; 180 181void CallGraph::initialize(Module &M) { 182 Mod = &M; 183} 184 185void CallGraph::destroy() { 186 if (FunctionMap.empty()) return; 187 188 // Reset all node's use counts to zero before deleting them to prevent an 189 // assertion from firing. 190#ifndef NDEBUG 191 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); 192 I != E; ++I) 193 I->second->allReferencesDropped(); 194#endif 195 196 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); 197 I != E; ++I) 198 delete I->second; 199 FunctionMap.clear(); 200} 201 202void CallGraph::print(raw_ostream &OS, Module*) const { 203 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I) 204 I->second->print(OS); 205} 206void CallGraph::dump() const { 207 print(dbgs(), 0); 208} 209 210//===----------------------------------------------------------------------===// 211// Implementations of public modification methods 212// 213 214// removeFunctionFromModule - Unlink the function from this module, returning 215// it. Because this removes the function from the module, the call graph node 216// is destroyed. This is only valid if the function does not call any other 217// functions (ie, there are no edges in it's CGN). The easiest way to do this 218// is to dropAllReferences before calling this. 219// 220Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) { 221 assert(CGN->empty() && "Cannot remove function from call " 222 "graph if it references other functions!"); 223 Function *F = CGN->getFunction(); // Get the function for the call graph node 224 delete CGN; // Delete the call graph node for this func 225 FunctionMap.erase(F); // Remove the call graph node from the map 226 227 Mod->getFunctionList().remove(F); 228 return F; 229} 230 231// getOrInsertFunction - This method is identical to calling operator[], but 232// it will insert a new CallGraphNode for the specified function if one does 233// not already exist. 234CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) { 235 CallGraphNode *&CGN = FunctionMap[F]; 236 if (CGN) return CGN; 237 238 assert((!F || F->getParent() == Mod) && "Function not in current module!"); 239 return CGN = new CallGraphNode(const_cast<Function*>(F)); 240} 241 242void CallGraphNode::print(raw_ostream &OS) const { 243 if (Function *F = getFunction()) 244 OS << "Call graph node for function: '" << F->getName() << "'"; 245 else 246 OS << "Call graph node <<null function>>"; 247 248 OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n'; 249 250 for (const_iterator I = begin(), E = end(); I != E; ++I) { 251 OS << " CS<" << I->first << "> calls "; 252 if (Function *FI = I->second->getFunction()) 253 OS << "function '" << FI->getName() <<"'\n"; 254 else 255 OS << "external node\n"; 256 } 257 OS << '\n'; 258} 259 260void CallGraphNode::dump() const { print(dbgs()); } 261 262/// removeCallEdgeFor - This method removes the edge in the node for the 263/// specified call site. Note that this method takes linear time, so it 264/// should be used sparingly. 265void CallGraphNode::removeCallEdgeFor(CallSite CS) { 266 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 267 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 268 if (I->first == CS.getInstruction()) { 269 I->second->DropRef(); 270 *I = CalledFunctions.back(); 271 CalledFunctions.pop_back(); 272 return; 273 } 274 } 275} 276 277 278// removeAnyCallEdgeTo - This method removes any call edges from this node to 279// the specified callee function. This takes more time to execute than 280// removeCallEdgeTo, so it should not be used unless necessary. 281void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) { 282 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i) 283 if (CalledFunctions[i].second == Callee) { 284 Callee->DropRef(); 285 CalledFunctions[i] = CalledFunctions.back(); 286 CalledFunctions.pop_back(); 287 --i; --e; 288 } 289} 290 291/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 292/// from this node to the specified callee function. 293void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) { 294 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 295 assert(I != CalledFunctions.end() && "Cannot find callee to remove!"); 296 CallRecord &CR = *I; 297 if (CR.second == Callee && CR.first == 0) { 298 Callee->DropRef(); 299 *I = CalledFunctions.back(); 300 CalledFunctions.pop_back(); 301 return; 302 } 303 } 304} 305 306/// replaceCallEdge - This method replaces the edge in the node for the 307/// specified call site with a new one. Note that this method takes linear 308/// time, so it should be used sparingly. 309void CallGraphNode::replaceCallEdge(CallSite CS, 310 CallSite NewCS, CallGraphNode *NewNode){ 311 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 312 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 313 if (I->first == CS.getInstruction()) { 314 I->second->DropRef(); 315 I->first = NewCS.getInstruction(); 316 I->second = NewNode; 317 NewNode->AddRef(); 318 return; 319 } 320 } 321} 322 323// Enuse that users of CallGraph.h also link with this file 324DEFINING_FILE_FOR(CallGraph) 325