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 and provides the BasicCallGraph
11 // default implementation.
13 //===----------------------------------------------------------------------===//
15 #include "llvm/Analysis/CallGraph.h"
16 #include "llvm/Module.h"
17 #include "llvm/Instructions.h"
18 #include "llvm/Support/CallSite.h"
22 static bool isOnlyADirectCall(Function *F, CallSite CS) {
23 if (!CS.getInstruction()) return false;
24 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
25 if (*I == F) return false;
31 //===----------------------------------------------------------------------===//
32 // BasicCallGraph class definition
34 class BasicCallGraph : public CallGraph, public ModulePass {
35 // Root is root of the call graph, or the external node if a 'main' function
40 // ExternalCallingNode - This node has edges to all external functions and
41 // those internal functions that have their address taken.
42 CallGraphNode *ExternalCallingNode;
44 // CallsExternalNode - This node has edges to it from all functions making
45 // indirect calls or calling an external function.
46 CallGraphNode *CallsExternalNode;
49 BasicCallGraph() : Root(0), ExternalCallingNode(0), CallsExternalNode(0) {}
50 ~BasicCallGraph() { destroy(); }
52 // runOnModule - Compute the call graph for the specified module.
53 virtual bool runOnModule(Module &M) {
55 CallGraph::initialize(M);
57 ExternalCallingNode = getOrInsertFunction(0);
58 CallsExternalNode = new CallGraphNode(0);
61 // Add every function to the call graph...
62 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
65 // If we didn't find a main function, use the external call graph node
66 if (Root == 0) Root = ExternalCallingNode;
71 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
75 virtual void print(std::ostream &o, const Module *M) const {
76 o << "CallGraph Root is: ";
77 if (Function *F = getRoot()->getFunction())
78 o << F->getName() << "\n";
80 o << "<<null function: 0x" << getRoot() << ">>\n";
82 CallGraph::print(o, M);
85 virtual void releaseMemory() {
89 /// dump - Print out this call graph.
91 inline void dump() const {
92 print(std::cerr, Mod);
95 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
96 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
98 // getRoot - Return the root of the call graph, which is either main, or if
99 // main cannot be found, the external node.
101 CallGraphNode *getRoot() { return Root; }
102 const CallGraphNode *getRoot() const { return Root; }
105 //===---------------------------------------------------------------------
106 // Implementation of CallGraph construction
109 // addToCallGraph - Add a function to the call graph, and link the node to all
110 // of the functions that it calls.
112 void addToCallGraph(Function *F) {
113 CallGraphNode *Node = getOrInsertFunction(F);
115 // If this function has external linkage, anything could call it...
116 if (!F->hasInternalLinkage()) {
117 ExternalCallingNode->addCalledFunction(Node);
119 // Found the entry point?
120 if (F->getName() == "main") {
121 if (Root) // Found multiple external mains? Don't pick one.
122 Root = ExternalCallingNode;
124 Root = Node; // Found a main, keep track of it!
128 // If this function is not defined in this translation unit, it could call
130 if (F->isExternal() && !F->getIntrinsicID())
131 Node->addCalledFunction(CallsExternalNode);
133 // Loop over all of the users of the function... looking for callers...
135 bool isUsedExternally = false;
136 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
137 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
138 if (isOnlyADirectCall(F, CallSite::get(Inst)))
139 getOrInsertFunction(Inst->getParent()->getParent())
140 ->addCalledFunction(Node);
142 isUsedExternally = true;
143 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
144 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
146 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
147 if (isOnlyADirectCall(F, CallSite::get(Inst)))
148 getOrInsertFunction(Inst->getParent()->getParent())
149 ->addCalledFunction(Node);
151 isUsedExternally = true;
153 isUsedExternally = true;
155 } else { // Can't classify the user!
156 isUsedExternally = true;
159 if (isUsedExternally)
160 ExternalCallingNode->addCalledFunction(Node);
162 // Look for an indirect function call...
163 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
164 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
166 CallSite CS = CallSite::get(II);
167 if (CS.getInstruction() && !CS.getCalledFunction())
168 Node->addCalledFunction(CallsExternalNode);
173 // destroy - Release memory for the call graph
174 virtual void destroy() {
175 if (!CallsExternalNode) {
176 delete CallsExternalNode;
177 CallsExternalNode = 0;
182 RegisterAnalysisGroup<CallGraph> X("Call Graph");
183 RegisterOpt<BasicCallGraph> Y("basiccg", "Basic CallGraph Construction");
184 RegisterAnalysisGroup<CallGraph, BasicCallGraph, true> Z;
186 } //End anonymous namespace
188 void CallGraph::initialize(Module &M) {
193 void CallGraph::destroy() {
194 if(!FunctionMap.size()) {
195 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
202 void CallGraph::print(std::ostream &OS, const Module *M) const {
203 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
204 I->second->print(OS);
207 void CallGraph::dump() const {
211 //===----------------------------------------------------------------------===//
212 // Implementations of public modification methods
215 // removeFunctionFromModule - Unlink the function from this module, returning
216 // it. Because this removes the function from the module, the call graph node
217 // is destroyed. This is only valid if the function does not call any other
218 // functions (ie, there are no edges in it's CGN). The easiest way to do this
219 // is to dropAllReferences before calling this.
221 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
222 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
223 "graph if it references other functions!");
224 Function *F = CGN->getFunction(); // Get the function for the call graph node
225 delete CGN; // Delete the call graph node for this func
226 FunctionMap.erase(F); // Remove the call graph node from the map
228 Mod->getFunctionList().remove(F);
232 // changeFunction - This method changes the function associated with this
233 // CallGraphNode, for use by transformations that need to change the prototype
234 // of a Function (thus they must create a new Function and move the old code
236 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
237 iterator I = FunctionMap.find(OldF);
238 CallGraphNode *&New = FunctionMap[NewF];
239 assert(I != FunctionMap.end() && I->second && !New &&
240 "OldF didn't exist in CG or NewF already does!");
243 FunctionMap.erase(I);
246 // getOrInsertFunction - This method is identical to calling operator[], but
247 // it will insert a new CallGraphNode for the specified function if one does
248 // not already exist.
249 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
250 CallGraphNode *&CGN = FunctionMap[F];
253 assert((!F || F->getParent() == Mod) && "Function not in current module!");
254 return CGN = new CallGraphNode(const_cast<Function*>(F));
257 void CallGraphNode::print(std::ostream &OS) const {
258 if (Function *F = getFunction())
259 OS << "Call graph node for function: '" << F->getName() <<"'\n";
261 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
263 for (const_iterator I = begin(), E = end(); I != E; ++I)
264 if ((*I)->getFunction())
265 OS << " Calls function '" << (*I)->getFunction()->getName() << "'\n";
267 OS << " Calls external node\n";
271 void CallGraphNode::dump() const { print(std::cerr); }
273 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
274 for (unsigned i = CalledFunctions.size(); ; --i) {
275 assert(i && "Cannot find callee to remove!");
276 if (CalledFunctions[i-1] == Callee) {
277 CalledFunctions.erase(CalledFunctions.begin()+i-1);
283 // removeAnyCallEdgeTo - This method removes any call edges from this node to
284 // the specified callee function. This takes more time to execute than
285 // removeCallEdgeTo, so it should not be used unless necessary.
286 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
287 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
288 if (CalledFunctions[i] == Callee) {
289 CalledFunctions[i] = CalledFunctions.back();
290 CalledFunctions.pop_back();
295 // Enuse that users of CallGraph.h also link with this file
296 DEFINING_FILE_FOR(CallGraph)