//===- CallGraph.cpp - Build a Module's call graph ------------------------===// // // The LLVM Compiler Infrastructure // // This file is distributed under the University of Illinois Open Source // License. See LICENSE.TXT for details. // //===----------------------------------------------------------------------===// #include "llvm/Analysis/CallGraph.h" #include "llvm/IR/CallSite.h" #include "llvm/IR/Instructions.h" #include "llvm/IR/IntrinsicInst.h" #include "llvm/IR/Module.h" #include "llvm/Support/Debug.h" #include "llvm/Support/raw_ostream.h" using namespace llvm; //===----------------------------------------------------------------------===// // Implementations of the CallGraph class methods. // CallGraph::CallGraph(Module &M) : M(M), Root(nullptr), ExternalCallingNode(getOrInsertFunction(nullptr)), CallsExternalNode(new CallGraphNode(nullptr)) { // Add every function to the call graph. for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I) addToCallGraph(I); // If we didn't find a main function, use the external call graph node if (!Root) Root = ExternalCallingNode; } CallGraph::~CallGraph() { // CallsExternalNode is not in the function map, delete it explicitly. CallsExternalNode->allReferencesDropped(); delete CallsExternalNode; // Reset all node's use counts to zero before deleting them to prevent an // assertion from firing. #ifndef NDEBUG for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); I != E; ++I) I->second->allReferencesDropped(); #endif for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end(); I != E; ++I) delete I->second; } void CallGraph::addToCallGraph(Function *F) { CallGraphNode *Node = getOrInsertFunction(F); // If this function has external linkage, anything could call it. if (!F->hasLocalLinkage()) { ExternalCallingNode->addCalledFunction(CallSite(), Node); // Found the entry point? if (F->getName() == "main") { if (Root) // Found multiple external mains? Don't pick one. Root = ExternalCallingNode; else Root = Node; // Found a main, keep track of it! } } // If this function has its address taken, anything could call it. if (F->hasAddressTaken()) ExternalCallingNode->addCalledFunction(CallSite(), Node); // If this function is not defined in this translation unit, it could call // anything. if (F->isDeclaration() && !F->isIntrinsic()) Node->addCalledFunction(CallSite(), CallsExternalNode); // Look for calls by this function. for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB) for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II) { CallSite CS(cast<Value>(II)); if (CS) { const Function *Callee = CS.getCalledFunction(); if (!Callee) // Indirect calls of intrinsics are not allowed so no need to check. Node->addCalledFunction(CS, CallsExternalNode); else if (!Callee->isIntrinsic()) Node->addCalledFunction(CS, getOrInsertFunction(Callee)); } } } void CallGraph::print(raw_ostream &OS) const { OS << "CallGraph Root is: "; if (Function *F = Root->getFunction()) OS << F->getName() << "\n"; else { OS << "<<null function: 0x" << Root << ">>\n"; } for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I) I->second->print(OS); } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void CallGraph::dump() const { print(dbgs()); } #endif // removeFunctionFromModule - Unlink the function from this module, returning // it. Because this removes the function from the module, the call graph node // is destroyed. This is only valid if the function does not call any other // functions (ie, there are no edges in it's CGN). The easiest way to do this // is to dropAllReferences before calling this. // Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) { assert(CGN->empty() && "Cannot remove function from call " "graph if it references other functions!"); Function *F = CGN->getFunction(); // Get the function for the call graph node delete CGN; // Delete the call graph node for this func FunctionMap.erase(F); // Remove the call graph node from the map M.getFunctionList().remove(F); return F; } /// spliceFunction - Replace the function represented by this node by another. /// This does not rescan the body of the function, so it is suitable when /// splicing the body of the old function to the new while also updating all /// callers from old to new. /// void CallGraph::spliceFunction(const Function *From, const Function *To) { assert(FunctionMap.count(From) && "No CallGraphNode for function!"); assert(!FunctionMap.count(To) && "Pointing CallGraphNode at a function that already exists"); FunctionMapTy::iterator I = FunctionMap.find(From); I->second->F = const_cast<Function*>(To); FunctionMap[To] = I->second; FunctionMap.erase(I); } // getOrInsertFunction - This method is identical to calling operator[], but // it will insert a new CallGraphNode for the specified function if one does // not already exist. CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) { CallGraphNode *&CGN = FunctionMap[F]; if (CGN) return CGN; assert((!F || F->getParent() == &M) && "Function not in current module!"); return CGN = new CallGraphNode(const_cast<Function*>(F)); } //===----------------------------------------------------------------------===// // Implementations of the CallGraphNode class methods. // void CallGraphNode::print(raw_ostream &OS) const { if (Function *F = getFunction()) OS << "Call graph node for function: '" << F->getName() << "'"; else OS << "Call graph node <<null function>>"; OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n'; for (const_iterator I = begin(), E = end(); I != E; ++I) { OS << " CS<" << I->first << "> calls "; if (Function *FI = I->second->getFunction()) OS << "function '" << FI->getName() <<"'\n"; else OS << "external node\n"; } OS << '\n'; } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void CallGraphNode::dump() const { print(dbgs()); } #endif /// removeCallEdgeFor - This method removes the edge in the node for the /// specified call site. Note that this method takes linear time, so it /// should be used sparingly. void CallGraphNode::removeCallEdgeFor(CallSite CS) { for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); if (I->first == CS.getInstruction()) { I->second->DropRef(); *I = CalledFunctions.back(); CalledFunctions.pop_back(); return; } } } // removeAnyCallEdgeTo - This method removes any call edges from this node to // the specified callee function. This takes more time to execute than // removeCallEdgeTo, so it should not be used unless necessary. void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) { for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i) if (CalledFunctions[i].second == Callee) { Callee->DropRef(); CalledFunctions[i] = CalledFunctions.back(); CalledFunctions.pop_back(); --i; --e; } } /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite /// from this node to the specified callee function. void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) { for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { assert(I != CalledFunctions.end() && "Cannot find callee to remove!"); CallRecord &CR = *I; if (CR.second == Callee && CR.first == nullptr) { Callee->DropRef(); *I = CalledFunctions.back(); CalledFunctions.pop_back(); return; } } } /// replaceCallEdge - This method replaces the edge in the node for the /// specified call site with a new one. Note that this method takes linear /// time, so it should be used sparingly. void CallGraphNode::replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode){ for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) { assert(I != CalledFunctions.end() && "Cannot find callsite to remove!"); if (I->first == CS.getInstruction()) { I->second->DropRef(); I->first = NewCS.getInstruction(); I->second = NewNode; NewNode->AddRef(); return; } } } //===----------------------------------------------------------------------===// // Out-of-line definitions of CallGraphAnalysis class members. // char CallGraphAnalysis::PassID; //===----------------------------------------------------------------------===// // Implementations of the CallGraphWrapperPass class methods. // CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) { initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry()); } CallGraphWrapperPass::~CallGraphWrapperPass() {} void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const { AU.setPreservesAll(); } bool CallGraphWrapperPass::runOnModule(Module &M) { // All the real work is done in the constructor for the CallGraph. G.reset(new CallGraph(M)); return false; } INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction", false, true) char CallGraphWrapperPass::ID = 0; void CallGraphWrapperPass::releaseMemory() { G.reset(); } void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const { if (!G) { OS << "No call graph has been built!\n"; return; } // Just delegate. G->print(OS); } #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP) void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); } #endif