1 //===- CallGraph.cpp - Build a Module's call graph ------------------------===//
3 // The LLVM Compiler Infrastructure
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.
8 //===----------------------------------------------------------------------===//
10 // This file implements the CallGraph class.
12 //===----------------------------------------------------------------------===//
14 #include "llvm/Analysis/CallGraph.h"
15 #include "llvm/Constants.h" // Remove when ConstantPointerRefs are gone
16 #include "llvm/Module.h"
17 #include "llvm/iOther.h"
18 #include "llvm/iTerminators.h"
19 #include "llvm/Support/CallSite.h"
20 #include "Support/STLExtras.h"
23 static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
25 // getNodeFor - Return the node for the specified function or create one if it
26 // does not already exist.
28 CallGraphNode *CallGraph::getNodeFor(Function *F) {
29 CallGraphNode *&CGN = FunctionMap[F];
32 assert((!F || F->getParent() == Mod) && "Function not in current module!");
33 return CGN = new CallGraphNode(F);
36 static bool isOnlyADirectCall(Function *F, CallSite CS) {
37 if (!CS.getInstruction()) return false;
38 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
39 if (*I == F) return false;
43 // addToCallGraph - Add a function to the call graph, and link the node to all
44 // of the functions that it calls.
46 void CallGraph::addToCallGraph(Function *F) {
47 CallGraphNode *Node = getNodeFor(F);
49 // If this function has external linkage, anything could call it...
50 if (!F->hasInternalLinkage()) {
51 ExternalCallingNode->addCalledFunction(Node);
53 // Found the entry point?
54 if (F->getName() == "main") {
55 if (Root) // Found multiple external mains? Don't pick one.
56 Root = ExternalCallingNode;
58 Root = Node; // Found a main, keep track of it!
62 // If this function is not defined in this translation unit, it could call
64 if (F->isExternal() && !F->getIntrinsicID())
65 Node->addCalledFunction(CallsExternalNode);
67 // Loop over all of the users of the function... looking for callers...
69 bool isUsedExternally = false;
70 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I) {
71 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
72 if (isOnlyADirectCall(F, CallSite::get(Inst)))
73 getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
75 isUsedExternally = true;
76 } else if (ConstantPointerRef *CPR = dyn_cast<ConstantPointerRef>(*I)) {
77 // THIS IS A DISGUSTING HACK. Brought to you by the power of
78 // ConstantPointerRefs!
79 for (Value::use_iterator I = CPR->use_begin(), E = CPR->use_end();
81 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
82 if (isOnlyADirectCall(F, CallSite::get(Inst)))
83 getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
85 isUsedExternally = true;
87 isUsedExternally = true;
89 } else { // Can't classify the user!
90 isUsedExternally = true;
94 ExternalCallingNode->addCalledFunction(Node);
96 // Look for an indirect function call...
97 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
98 for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II){
99 CallSite CS = CallSite::get(II);
100 if (CS.getInstruction() && !CS.getCalledFunction())
101 Node->addCalledFunction(CallsExternalNode);
105 bool CallGraph::run(Module &M) {
109 ExternalCallingNode = getNodeFor(0);
110 CallsExternalNode = new CallGraphNode(0);
113 // Add every function to the call graph...
114 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
117 // If we didn't find a main function, use the external call graph node
118 if (Root == 0) Root = ExternalCallingNode;
123 void CallGraph::destroy() {
124 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
130 static void WriteToOutput(const CallGraphNode *CGN, std::ostream &o) {
131 if (CGN->getFunction())
132 o << "Call graph node for function: '"
133 << CGN->getFunction()->getName() <<"'\n";
135 o << "Call graph node <<null function: 0x" << CGN << ">>:\n";
137 for (unsigned i = 0; i < CGN->size(); ++i)
138 if ((*CGN)[i]->getFunction())
139 o << " Calls function '" << (*CGN)[i]->getFunction()->getName() << "'\n";
141 o << " Calls external node\n";
145 void CallGraph::print(std::ostream &o, const Module *M) const {
146 o << "CallGraph Root is: ";
147 if (getRoot()->getFunction())
148 o << getRoot()->getFunction()->getName() << "\n";
150 o << "<<null function: 0x" << getRoot() << ">>\n";
152 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
153 WriteToOutput(I->second, o);
157 //===----------------------------------------------------------------------===//
158 // Implementations of public modification methods
161 // Functions to keep a call graph up to date with a function that has been
164 void CallGraph::addFunctionToModule(Function *F) {
165 assert(0 && "not implemented");
169 // removeFunctionFromModule - Unlink the function from this module, returning
170 // it. Because this removes the function from the module, the call graph node
171 // is destroyed. This is only valid if the function does not call any other
172 // functions (ie, there are no edges in it's CGN). The easiest way to do this
173 // is to dropAllReferences before calling this.
175 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
176 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
177 "graph if it references other functions!");
178 Function *F = CGN->getFunction(); // Get the function for the call graph node
179 delete CGN; // Delete the call graph node for this func
180 FunctionMap.erase(F); // Remove the call graph node from the map
182 Mod->getFunctionList().remove(F);
186 void CallGraph::stub() {}
188 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
189 for (unsigned i = CalledFunctions.size(); ; --i) {
190 assert(i && "Cannot find callee to remove!");
191 if (CalledFunctions[i-1] == Callee) {
192 CalledFunctions.erase(CalledFunctions.begin()+i-1);