CallGraph.cpp revision 198892
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/raw_ostream.h" 21using namespace llvm; 22 23namespace { 24 25//===----------------------------------------------------------------------===// 26// BasicCallGraph class definition 27// 28class BasicCallGraph : public CallGraph, public ModulePass { 29 // Root is root of the call graph, or the external node if a 'main' function 30 // couldn't be found. 31 // 32 CallGraphNode *Root; 33 34 // ExternalCallingNode - This node has edges to all external functions and 35 // those internal functions that have their address taken. 36 CallGraphNode *ExternalCallingNode; 37 38 // CallsExternalNode - This node has edges to it from all functions making 39 // indirect calls or calling an external function. 40 CallGraphNode *CallsExternalNode; 41 42public: 43 static char ID; // Class identification, replacement for typeinfo 44 BasicCallGraph() : ModulePass(&ID), Root(0), 45 ExternalCallingNode(0), CallsExternalNode(0) {} 46 47 // runOnModule - Compute the call graph for the specified module. 48 virtual bool runOnModule(Module &M) { 49 CallGraph::initialize(M); 50 51 ExternalCallingNode = getOrInsertFunction(0); 52 CallsExternalNode = new CallGraphNode(0); 53 Root = 0; 54 55 // Add every function to the call graph. 56 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) 57 addToCallGraph(I); 58 59 // If we didn't find a main function, use the external call graph node 60 if (Root == 0) Root = ExternalCallingNode; 61 62 return false; 63 } 64 65 virtual void getAnalysisUsage(AnalysisUsage &AU) const { 66 AU.setPreservesAll(); 67 } 68 69 virtual void print(raw_ostream &OS, const Module *) const { 70 OS << "CallGraph Root is: "; 71 if (Function *F = getRoot()->getFunction()) 72 OS << F->getName() << "\n"; 73 else { 74 OS << "<<null function: 0x" << getRoot() << ">>\n"; 75 } 76 77 CallGraph::print(OS, 0); 78 } 79 80 virtual void releaseMemory() { 81 destroy(); 82 } 83 84 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; } 85 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; } 86 87 // getRoot - Return the root of the call graph, which is either main, or if 88 // main cannot be found, the external node. 89 // 90 CallGraphNode *getRoot() { return Root; } 91 const CallGraphNode *getRoot() const { return Root; } 92 93private: 94 //===--------------------------------------------------------------------- 95 // Implementation of CallGraph construction 96 // 97 98 // addToCallGraph - Add a function to the call graph, and link the node to all 99 // of the functions that it calls. 100 // 101 void addToCallGraph(Function *F) { 102 CallGraphNode *Node = getOrInsertFunction(F); 103 104 // If this function has external linkage, anything could call it. 105 if (!F->hasLocalLinkage()) { 106 ExternalCallingNode->addCalledFunction(CallSite(), Node); 107 108 // Found the entry point? 109 if (F->getName() == "main") { 110 if (Root) // Found multiple external mains? Don't pick one. 111 Root = ExternalCallingNode; 112 else 113 Root = Node; // Found a main, keep track of it! 114 } 115 } 116 117 // Loop over all of the users of the function, looking for non-call uses. 118 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I) 119 if ((!isa<CallInst>(I) && !isa<InvokeInst>(I)) 120 || !CallSite(cast<Instruction>(I)).isCallee(I)) { 121 // Not a call, or being used as a parameter rather than as the callee. 122 ExternalCallingNode->addCalledFunction(CallSite(), Node); 123 break; 124 } 125 126 // If this function is not defined in this translation unit, it could call 127 // anything. 128 if (F->isDeclaration() && !F->isIntrinsic()) 129 Node->addCalledFunction(CallSite(), CallsExternalNode); 130 131 // Look for calls by this function. 132 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB) 133 for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); 134 II != IE; ++II) { 135 CallSite CS = CallSite::get(II); 136 if (CS.getInstruction() && !isa<DbgInfoIntrinsic>(II)) { 137 const Function *Callee = CS.getCalledFunction(); 138 if (Callee) 139 Node->addCalledFunction(CS, getOrInsertFunction(Callee)); 140 else 141 Node->addCalledFunction(CS, CallsExternalNode); 142 } 143 } 144 } 145 146 // 147 // destroy - Release memory for the call graph 148 virtual void destroy() { 149 /// CallsExternalNode is not in the function map, delete it explicitly. 150 delete CallsExternalNode; 151 CallsExternalNode = 0; 152 CallGraph::destroy(); 153 } 154}; 155 156} //End anonymous namespace 157 158static RegisterAnalysisGroup<CallGraph> X("Call Graph"); 159static RegisterPass<BasicCallGraph> 160Y("basiccg", "Basic CallGraph Construction", false, true); 161static RegisterAnalysisGroup<CallGraph, true> Z(Y); 162 163char CallGraph::ID = 0; 164char BasicCallGraph::ID = 0; 165 166void CallGraph::initialize(Module &M) { 167 Mod = &M; 168} 169 170void CallGraph::destroy() { 171 if (FunctionMap.empty()) return; 172 173 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); 174 I != E; ++I) 175 delete I->second; 176 FunctionMap.clear(); 177} 178 179void CallGraph::print(raw_ostream &OS, Module*) const { 180 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I) 181 I->second->print(OS); 182} 183void CallGraph::dump() const { 184 print(errs(), 0); 185} 186 187//===----------------------------------------------------------------------===// 188// Implementations of public modification methods 189// 190 191// removeFunctionFromModule - Unlink the function from this module, returning 192// it. Because this removes the function from the module, the call graph node 193// is destroyed. This is only valid if the function does not call any other 194// functions (ie, there are no edges in it's CGN). The easiest way to do this 195// is to dropAllReferences before calling this. 196// 197Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) { 198 assert(CGN->empty() && "Cannot remove function from call " 199 "graph if it references other functions!"); 200 Function *F = CGN->getFunction(); // Get the function for the call graph node 201 delete CGN; // Delete the call graph node for this func 202 FunctionMap.erase(F); // Remove the call graph node from the map 203 204 Mod->getFunctionList().remove(F); 205 return F; 206} 207 208// getOrInsertFunction - This method is identical to calling operator[], but 209// it will insert a new CallGraphNode for the specified function if one does 210// not already exist. 211CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) { 212 CallGraphNode *&CGN = FunctionMap[F]; 213 if (CGN) return CGN; 214 215 assert((!F || F->getParent() == Mod) && "Function not in current module!"); 216 return CGN = new CallGraphNode(const_cast<Function*>(F)); 217} 218 219void CallGraphNode::print(raw_ostream &OS) const { 220 if (Function *F = getFunction()) 221 OS << "Call graph node for function: '" << F->getName() << "'"; 222 else 223 OS << "Call graph node <<null function>>"; 224 225 OS << "<<0x" << this << ">> #uses=" << getNumReferences() << '\n'; 226 227 for (const_iterator I = begin(), E = end(); I != E; ++I) 228 if (Function *FI = I->second->getFunction()) 229 OS << " Calls function '" << FI->getName() <<"'\n"; 230 else 231 OS << " Calls external node\n"; 232 OS << "\n"; 233} 234 235void CallGraphNode::dump() const { print(errs()); } 236 237/// removeCallEdgeFor - This method removes the edge in the node for the 238/// specified call site. Note that this method takes linear time, so it 239/// should be used sparingly. 240void CallGraphNode::removeCallEdgeFor(CallSite CS) { 241 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 242 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 243 if (I->first == CS.getInstruction()) { 244 I->second->DropRef(); 245 *I = CalledFunctions.back(); 246 CalledFunctions.pop_back(); 247 return; 248 } 249 } 250} 251 252 253// removeAnyCallEdgeTo - This method removes any call edges from this node to 254// the specified callee function. This takes more time to execute than 255// removeCallEdgeTo, so it should not be used unless necessary. 256void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) { 257 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i) 258 if (CalledFunctions[i].second == Callee) { 259 Callee->DropRef(); 260 CalledFunctions[i] = CalledFunctions.back(); 261 CalledFunctions.pop_back(); 262 --i; --e; 263 } 264} 265 266/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 267/// from this node to the specified callee function. 268void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) { 269 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 270 assert(I != CalledFunctions.end() && "Cannot find callee to remove!"); 271 CallRecord &CR = *I; 272 if (CR.second == Callee && CR.first == 0) { 273 Callee->DropRef(); 274 *I = CalledFunctions.back(); 275 CalledFunctions.pop_back(); 276 return; 277 } 278 } 279} 280 281/// replaceCallEdge - This method replaces the edge in the node for the 282/// specified call site with a new one. Note that this method takes linear 283/// time, so it should be used sparingly. 284void CallGraphNode::replaceCallEdge(CallSite CS, 285 CallSite NewCS, CallGraphNode *NewNode){ 286 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 287 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 288 if (I->first == CS.getInstruction()) { 289 I->second->DropRef(); 290 I->first = NewCS.getInstruction(); 291 I->second = NewNode; 292 NewNode->AddRef(); 293 return; 294 } 295 } 296} 297 298// Enuse that users of CallGraph.h also link with this file 299DEFINING_FILE_FOR(CallGraph) 300