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/Module.h"
16 #include "llvm/Instructions.h"
17 #include "llvm/Support/CallSite.h"
18 #include "llvm/ADT/STLExtras.h"
22 static RegisterAnalysis<CallGraph> X("callgraph", "Call Graph Construction");
24 // getNodeFor - Return the node for the specified function or create one if it
25 // does not already exist.
27 CallGraphNode *CallGraph::getNodeFor(Function *F) {
28 CallGraphNode *&CGN = FunctionMap[F];
31 assert((!F || F->getParent() == Mod) && "Function not in current module!");
32 return CGN = new CallGraphNode(F);
35 static bool isOnlyADirectCall(Function *F, CallSite CS) {
36 if (!CS.getInstruction()) return false;
37 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
38 if (*I == F) return false;
42 // addToCallGraph - Add a function to the call graph, and link the node to all
43 // of the functions that it calls.
45 void CallGraph::addToCallGraph(Function *F) {
46 CallGraphNode *Node = getNodeFor(F);
48 // If this function has external linkage, anything could call it...
49 if (!F->hasInternalLinkage()) {
50 ExternalCallingNode->addCalledFunction(Node);
52 // Found the entry point?
53 if (F->getName() == "main") {
54 if (Root) // Found multiple external mains? Don't pick one.
55 Root = ExternalCallingNode;
57 Root = Node; // Found a main, keep track of it!
61 // If this function is not defined in this translation unit, it could call
63 if (F->isExternal() && !F->getIntrinsicID())
64 Node->addCalledFunction(CallsExternalNode);
66 // Loop over all of the users of the function... looking for callers...
68 bool isUsedExternally = false;
69 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I) {
70 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
71 if (isOnlyADirectCall(F, CallSite::get(Inst)))
72 getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
74 isUsedExternally = true;
75 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
76 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
78 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
79 if (isOnlyADirectCall(F, CallSite::get(Inst)))
80 getNodeFor(Inst->getParent()->getParent())->addCalledFunction(Node);
82 isUsedExternally = true;
84 isUsedExternally = true;
86 } else { // Can't classify the user!
87 isUsedExternally = true;
91 ExternalCallingNode->addCalledFunction(Node);
93 // Look for an indirect function call...
94 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
95 for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE; ++II){
96 CallSite CS = CallSite::get(II);
97 if (CS.getInstruction() && !CS.getCalledFunction())
98 Node->addCalledFunction(CallsExternalNode);
102 bool CallGraph::runOnModule(Module &M) {
106 ExternalCallingNode = getNodeFor(0);
107 CallsExternalNode = new CallGraphNode(0);
110 // Add every function to the call graph...
111 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
114 // If we didn't find a main function, use the external call graph node
115 if (Root == 0) Root = ExternalCallingNode;
120 void CallGraph::destroy() {
121 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
125 delete CallsExternalNode;
126 CallsExternalNode = 0;
129 void CallGraphNode::print(std::ostream &OS) const {
130 if (Function *F = getFunction())
131 OS << "Call graph node for function: '" << F->getName() <<"'\n";
133 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
135 for (const_iterator I = begin(), E = end(); I != E; ++I)
136 if ((*I)->getFunction())
137 OS << " Calls function '" << (*I)->getFunction()->getName() << "'\n";
139 OS << " Calls external node\n";
143 void CallGraphNode::dump() const { print(std::cerr); }
145 void CallGraph::print(std::ostream &OS, const Module *M) const {
146 OS << "CallGraph Root is: ";
147 if (Function *F = getRoot()->getFunction())
148 OS << F->getName() << "\n";
150 OS << "<<null function: 0x" << getRoot() << ">>\n";
152 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
153 I->second->print(OS);
156 void CallGraph::dump() const {
161 //===----------------------------------------------------------------------===//
162 // Implementations of public modification methods
165 // removeFunctionFromModule - Unlink the function from this module, returning
166 // it. Because this removes the function from the module, the call graph node
167 // is destroyed. This is only valid if the function does not call any other
168 // functions (ie, there are no edges in it's CGN). The easiest way to do this
169 // is to dropAllReferences before calling this.
171 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
172 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
173 "graph if it references other functions!");
174 Function *F = CGN->getFunction(); // Get the function for the call graph node
175 delete CGN; // Delete the call graph node for this func
176 FunctionMap.erase(F); // Remove the call graph node from the map
178 Mod->getFunctionList().remove(F);
182 // changeFunction - This method changes the function associated with this
183 // CallGraphNode, for use by transformations that need to change the prototype
184 // of a Function (thus they must create a new Function and move the old code
186 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
187 iterator I = FunctionMap.find(OldF);
188 CallGraphNode *&New = FunctionMap[NewF];
189 assert(I != FunctionMap.end() && I->second && !New &&
190 "OldF didn't exist in CG or NewF already does!");
193 FunctionMap.erase(I);
197 void CallGraph::stub() {}
199 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
200 for (unsigned i = CalledFunctions.size(); ; --i) {
201 assert(i && "Cannot find callee to remove!");
202 if (CalledFunctions[i-1] == Callee) {
203 CalledFunctions.erase(CalledFunctions.begin()+i-1);
209 // removeAnyCallEdgeTo - This method removes any call edges from this node to
210 // the specified callee function. This takes more time to execute than
211 // removeCallEdgeTo, so it should not be used unless necessary.
212 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
213 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
214 if (CalledFunctions[i] == Callee) {
215 CalledFunctions[i] = CalledFunctions.back();
216 CalledFunctions.pop_back();