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#include "llvm/Analysis/CallGraph.h" 11#include "llvm/IR/CallSite.h" 12#include "llvm/IR/Instructions.h" 13#include "llvm/IR/IntrinsicInst.h" 14#include "llvm/IR/Module.h" 15#include "llvm/Support/Debug.h" 16#include "llvm/Support/raw_ostream.h" 17using namespace llvm; 18 19//===----------------------------------------------------------------------===// 20// Implementations of the CallGraph class methods. 21// 22 23CallGraph::CallGraph(Module &M) 24 : M(M), Root(nullptr), ExternalCallingNode(getOrInsertFunction(nullptr)), 25 CallsExternalNode(llvm::make_unique<CallGraphNode>(nullptr)) { 26 // Add every function to the call graph. 27 for (Function &F : M) 28 addToCallGraph(&F); 29 30 // If we didn't find a main function, use the external call graph node 31 if (!Root) 32 Root = ExternalCallingNode; 33} 34 35CallGraph::CallGraph(CallGraph &&Arg) 36 : M(Arg.M), FunctionMap(std::move(Arg.FunctionMap)), Root(Arg.Root), 37 ExternalCallingNode(Arg.ExternalCallingNode), 38 CallsExternalNode(std::move(Arg.CallsExternalNode)) { 39 Arg.FunctionMap.clear(); 40 Arg.Root = nullptr; 41 Arg.ExternalCallingNode = nullptr; 42} 43 44CallGraph::~CallGraph() { 45 // CallsExternalNode is not in the function map, delete it explicitly. 46 if (CallsExternalNode) 47 CallsExternalNode->allReferencesDropped(); 48 49// Reset all node's use counts to zero before deleting them to prevent an 50// assertion from firing. 51#ifndef NDEBUG 52 for (auto &I : FunctionMap) 53 I.second->allReferencesDropped(); 54#endif 55} 56 57void CallGraph::addToCallGraph(Function *F) { 58 CallGraphNode *Node = getOrInsertFunction(F); 59 60 // If this function has external linkage, anything could call it. 61 if (!F->hasLocalLinkage()) { 62 ExternalCallingNode->addCalledFunction(CallSite(), Node); 63 64 // Found the entry point? 65 if (F->getName() == "main") { 66 if (Root) // Found multiple external mains? Don't pick one. 67 Root = ExternalCallingNode; 68 else 69 Root = Node; // Found a main, keep track of it! 70 } 71 } 72 73 // If this function has its address taken, anything could call it. 74 if (F->hasAddressTaken()) 75 ExternalCallingNode->addCalledFunction(CallSite(), Node); 76 77 // If this function is not defined in this translation unit, it could call 78 // anything. 79 if (F->isDeclaration() && !F->isIntrinsic()) 80 Node->addCalledFunction(CallSite(), CallsExternalNode.get()); 81 82 // Look for calls by this function. 83 for (BasicBlock &BB : *F) 84 for (Instruction &I : BB) { 85 if (auto CS = CallSite(&I)) { 86 const Function *Callee = CS.getCalledFunction(); 87 if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID())) 88 // Indirect calls of intrinsics are not allowed so no need to check. 89 // We can be more precise here by using TargetArg returned by 90 // Intrinsic::isLeaf. 91 Node->addCalledFunction(CS, CallsExternalNode.get()); 92 else if (!Callee->isIntrinsic()) 93 Node->addCalledFunction(CS, getOrInsertFunction(Callee)); 94 } 95 } 96} 97 98void CallGraph::print(raw_ostream &OS) const { 99 OS << "CallGraph Root is: "; 100 if (Function *F = Root->getFunction()) 101 OS << F->getName() << "\n"; 102 else { 103 OS << "<<null function: 0x" << Root << ">>\n"; 104 } 105 106 // Print in a deterministic order by sorting CallGraphNodes by name. We do 107 // this here to avoid slowing down the non-printing fast path. 108 109 SmallVector<CallGraphNode *, 16> Nodes; 110 Nodes.reserve(FunctionMap.size()); 111 112 for (const auto &I : *this) 113 Nodes.push_back(I.second.get()); 114 115 std::sort(Nodes.begin(), Nodes.end(), 116 [](CallGraphNode *LHS, CallGraphNode *RHS) { 117 if (Function *LF = LHS->getFunction()) 118 if (Function *RF = RHS->getFunction()) 119 return LF->getName() < RF->getName(); 120 121 return RHS->getFunction() != nullptr; 122 }); 123 124 for (CallGraphNode *CN : Nodes) 125 CN->print(OS); 126} 127 128LLVM_DUMP_METHOD 129void CallGraph::dump() const { print(dbgs()); } 130 131// removeFunctionFromModule - Unlink the function from this module, returning 132// it. Because this removes the function from the module, the call graph node 133// is destroyed. This is only valid if the function does not call any other 134// functions (ie, there are no edges in it's CGN). The easiest way to do this 135// is to dropAllReferences before calling this. 136// 137Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) { 138 assert(CGN->empty() && "Cannot remove function from call " 139 "graph if it references other functions!"); 140 Function *F = CGN->getFunction(); // Get the function for the call graph node 141 FunctionMap.erase(F); // Remove the call graph node from the map 142 143 M.getFunctionList().remove(F); 144 return F; 145} 146 147/// spliceFunction - Replace the function represented by this node by another. 148/// This does not rescan the body of the function, so it is suitable when 149/// splicing the body of the old function to the new while also updating all 150/// callers from old to new. 151/// 152void CallGraph::spliceFunction(const Function *From, const Function *To) { 153 assert(FunctionMap.count(From) && "No CallGraphNode for function!"); 154 assert(!FunctionMap.count(To) && 155 "Pointing CallGraphNode at a function that already exists"); 156 FunctionMapTy::iterator I = FunctionMap.find(From); 157 I->second->F = const_cast<Function*>(To); 158 FunctionMap[To] = std::move(I->second); 159 FunctionMap.erase(I); 160} 161 162// getOrInsertFunction - This method is identical to calling operator[], but 163// it will insert a new CallGraphNode for the specified function if one does 164// not already exist. 165CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) { 166 auto &CGN = FunctionMap[F]; 167 if (CGN) 168 return CGN.get(); 169 170 assert((!F || F->getParent() == &M) && "Function not in current module!"); 171 CGN = llvm::make_unique<CallGraphNode>(const_cast<Function *>(F)); 172 return CGN.get(); 173} 174 175//===----------------------------------------------------------------------===// 176// Implementations of the CallGraphNode class methods. 177// 178 179void CallGraphNode::print(raw_ostream &OS) const { 180 if (Function *F = getFunction()) 181 OS << "Call graph node for function: '" << F->getName() << "'"; 182 else 183 OS << "Call graph node <<null function>>"; 184 185 OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n'; 186 187 for (const auto &I : *this) { 188 OS << " CS<" << I.first << "> calls "; 189 if (Function *FI = I.second->getFunction()) 190 OS << "function '" << FI->getName() <<"'\n"; 191 else 192 OS << "external node\n"; 193 } 194 OS << '\n'; 195} 196 197LLVM_DUMP_METHOD 198void CallGraphNode::dump() const { print(dbgs()); } 199 200/// removeCallEdgeFor - This method removes the edge in the node for the 201/// specified call site. Note that this method takes linear time, so it 202/// should be used sparingly. 203void CallGraphNode::removeCallEdgeFor(CallSite CS) { 204 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 205 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 206 if (I->first == CS.getInstruction()) { 207 I->second->DropRef(); 208 *I = CalledFunctions.back(); 209 CalledFunctions.pop_back(); 210 return; 211 } 212 } 213} 214 215// removeAnyCallEdgeTo - This method removes any call edges from this node to 216// the specified callee function. This takes more time to execute than 217// removeCallEdgeTo, so it should not be used unless necessary. 218void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) { 219 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i) 220 if (CalledFunctions[i].second == Callee) { 221 Callee->DropRef(); 222 CalledFunctions[i] = CalledFunctions.back(); 223 CalledFunctions.pop_back(); 224 --i; --e; 225 } 226} 227 228/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite 229/// from this node to the specified callee function. 230void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) { 231 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 232 assert(I != CalledFunctions.end() && "Cannot find callee to remove!"); 233 CallRecord &CR = *I; 234 if (CR.second == Callee && CR.first == nullptr) { 235 Callee->DropRef(); 236 *I = CalledFunctions.back(); 237 CalledFunctions.pop_back(); 238 return; 239 } 240 } 241} 242 243/// replaceCallEdge - This method replaces the edge in the node for the 244/// specified call site with a new one. Note that this method takes linear 245/// time, so it should be used sparingly. 246void CallGraphNode::replaceCallEdge(CallSite CS, 247 CallSite NewCS, CallGraphNode *NewNode){ 248 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { 249 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); 250 if (I->first == CS.getInstruction()) { 251 I->second->DropRef(); 252 I->first = NewCS.getInstruction(); 253 I->second = NewNode; 254 NewNode->AddRef(); 255 return; 256 } 257 } 258} 259 260// Provide an explicit template instantiation for the static ID. 261char CallGraphAnalysis::PassID; 262 263PreservedAnalyses CallGraphPrinterPass::run(Module &M, 264 AnalysisManager<Module> &AM) { 265 AM.getResult<CallGraphAnalysis>(M).print(OS); 266 return PreservedAnalyses::all(); 267} 268 269//===----------------------------------------------------------------------===// 270// Out-of-line definitions of CallGraphAnalysis class members. 271// 272 273//===----------------------------------------------------------------------===// 274// Implementations of the CallGraphWrapperPass class methods. 275// 276 277CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) { 278 initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry()); 279} 280 281CallGraphWrapperPass::~CallGraphWrapperPass() {} 282 283void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { 284 AU.setPreservesAll(); 285} 286 287bool CallGraphWrapperPass::runOnModule(Module &M) { 288 // All the real work is done in the constructor for the CallGraph. 289 G.reset(new CallGraph(M)); 290 return false; 291} 292 293INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction", 294 false, true) 295 296char CallGraphWrapperPass::ID = 0; 297 298void CallGraphWrapperPass::releaseMemory() { G.reset(); } 299 300void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const { 301 if (!G) { 302 OS << "No call graph has been built!\n"; 303 return; 304 } 305 306 // Just delegate. 307 G->print(OS); 308} 309 310LLVM_DUMP_METHOD 311void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); } 312 313namespace { 314struct CallGraphPrinterLegacyPass : public ModulePass { 315 static char ID; // Pass ID, replacement for typeid 316 CallGraphPrinterLegacyPass() : ModulePass(ID) { 317 initializeCallGraphPrinterLegacyPassPass(*PassRegistry::getPassRegistry()); 318 } 319 320 void getAnalysisUsage(AnalysisUsage &AU) const override { 321 AU.setPreservesAll(); 322 AU.addRequiredTransitive<CallGraphWrapperPass>(); 323 } 324 bool runOnModule(Module &M) override { 325 getAnalysis<CallGraphWrapperPass>().print(errs(), &M); 326 return false; 327 } 328}; 329} 330 331char CallGraphPrinterLegacyPass::ID = 0; 332 333INITIALIZE_PASS_BEGIN(CallGraphPrinterLegacyPass, "print-callgraph", 334 "Print a call graph", true, true) 335INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass) 336INITIALIZE_PASS_END(CallGraphPrinterLegacyPass, "print-callgraph", 337 "Print a call graph", true, true) 338