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"
19 #include "llvm/Support/Streams.h"
23 static bool isOnlyADirectCall(Function *F, CallSite CS) {
24 if (!CS.getInstruction()) return false;
25 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
26 if (*I == F) return false;
32 //===----------------------------------------------------------------------===//
33 // BasicCallGraph class definition
35 class BasicCallGraph : public CallGraph, public ModulePass {
36 // Root is root of the call graph, or the external node if a 'main' function
41 // ExternalCallingNode - This node has edges to all external functions and
42 // those internal functions that have their address taken.
43 CallGraphNode *ExternalCallingNode;
45 // CallsExternalNode - This node has edges to it from all functions making
46 // indirect calls or calling an external function.
47 CallGraphNode *CallsExternalNode;
50 BasicCallGraph() : Root(0), ExternalCallingNode(0), CallsExternalNode(0) {}
51 ~BasicCallGraph() { destroy(); }
53 // runOnModule - Compute the call graph for the specified module.
54 virtual bool runOnModule(Module &M) {
56 CallGraph::initialize(M);
58 ExternalCallingNode = getOrInsertFunction(0);
59 CallsExternalNode = new CallGraphNode(0);
62 // Add every function to the call graph...
63 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
66 // If we didn't find a main function, use the external call graph node
67 if (Root == 0) Root = ExternalCallingNode;
72 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
76 void print(llvm_ostream &o, const Module *M) const {
77 if (o.stream()) print(*o.stream(), M);
80 virtual void print(std::ostream &o, const Module *M) const {
81 o << "CallGraph Root is: ";
82 if (Function *F = getRoot()->getFunction())
83 o << F->getName() << "\n";
85 o << "<<null function: 0x" << getRoot() << ">>\n";
87 CallGraph::print(o, M);
90 virtual void releaseMemory() {
94 /// dump - Print out this call graph.
96 inline void dump() const {
97 print(llvm_cerr, Mod);
100 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
101 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
103 // getRoot - Return the root of the call graph, which is either main, or if
104 // main cannot be found, the external node.
106 CallGraphNode *getRoot() { return Root; }
107 const CallGraphNode *getRoot() const { return Root; }
110 //===---------------------------------------------------------------------
111 // Implementation of CallGraph construction
114 // addToCallGraph - Add a function to the call graph, and link the node to all
115 // of the functions that it calls.
117 void addToCallGraph(Function *F) {
118 CallGraphNode *Node = getOrInsertFunction(F);
120 // If this function has external linkage, anything could call it.
121 if (!F->hasInternalLinkage()) {
122 ExternalCallingNode->addCalledFunction(CallSite(), Node);
124 // Found the entry point?
125 if (F->getName() == "main") {
126 if (Root) // Found multiple external mains? Don't pick one.
127 Root = ExternalCallingNode;
129 Root = Node; // Found a main, keep track of it!
133 // If this function is not defined in this translation unit, it could call
135 if (F->isExternal() && !F->getIntrinsicID())
136 Node->addCalledFunction(CallSite(), CallsExternalNode);
138 // Loop over all of the users of the function... looking for callers...
140 bool isUsedExternally = false;
141 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
142 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
143 CallSite CS = CallSite::get(Inst);
144 if (isOnlyADirectCall(F, CS))
145 getOrInsertFunction(Inst->getParent()->getParent())
146 ->addCalledFunction(CS, Node);
148 isUsedExternally = true;
149 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
150 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
152 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
153 CallSite CS = CallSite::get(Inst);
154 if (isOnlyADirectCall(F, CS))
155 getOrInsertFunction(Inst->getParent()->getParent())
156 ->addCalledFunction(CS, Node);
158 isUsedExternally = true;
160 isUsedExternally = true;
162 } else { // Can't classify the user!
163 isUsedExternally = true;
166 if (isUsedExternally)
167 ExternalCallingNode->addCalledFunction(CallSite(), Node);
169 // Look for an indirect function call.
170 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
171 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
173 CallSite CS = CallSite::get(II);
174 if (CS.getInstruction() && !CS.getCalledFunction())
175 Node->addCalledFunction(CS, CallsExternalNode);
180 // destroy - Release memory for the call graph
181 virtual void destroy() {
182 if (!CallsExternalNode) {
183 delete CallsExternalNode;
184 CallsExternalNode = 0;
189 RegisterAnalysisGroup<CallGraph> X("Call Graph");
190 RegisterPass<BasicCallGraph> Y("basiccg", "Basic CallGraph Construction");
191 RegisterAnalysisGroup<CallGraph, true> Z(Y);
193 } //End anonymous namespace
195 void CallGraph::initialize(Module &M) {
200 void CallGraph::destroy() {
201 if (!FunctionMap.empty()) {
202 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
209 void CallGraph::print(std::ostream &OS, const Module *M) const {
210 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
211 I->second->print(OS);
214 void CallGraph::dump() const {
218 //===----------------------------------------------------------------------===//
219 // Implementations of public modification methods
222 // removeFunctionFromModule - Unlink the function from this module, returning
223 // it. Because this removes the function from the module, the call graph node
224 // is destroyed. This is only valid if the function does not call any other
225 // functions (ie, there are no edges in it's CGN). The easiest way to do this
226 // is to dropAllReferences before calling this.
228 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
229 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
230 "graph if it references other functions!");
231 Function *F = CGN->getFunction(); // Get the function for the call graph node
232 delete CGN; // Delete the call graph node for this func
233 FunctionMap.erase(F); // Remove the call graph node from the map
235 Mod->getFunctionList().remove(F);
239 // changeFunction - This method changes the function associated with this
240 // CallGraphNode, for use by transformations that need to change the prototype
241 // of a Function (thus they must create a new Function and move the old code
243 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
244 iterator I = FunctionMap.find(OldF);
245 CallGraphNode *&New = FunctionMap[NewF];
246 assert(I != FunctionMap.end() && I->second && !New &&
247 "OldF didn't exist in CG or NewF already does!");
250 FunctionMap.erase(I);
253 // getOrInsertFunction - This method is identical to calling operator[], but
254 // it will insert a new CallGraphNode for the specified function if one does
255 // not already exist.
256 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
257 CallGraphNode *&CGN = FunctionMap[F];
260 assert((!F || F->getParent() == Mod) && "Function not in current module!");
261 return CGN = new CallGraphNode(const_cast<Function*>(F));
264 void CallGraphNode::print(std::ostream &OS) const {
265 if (Function *F = getFunction())
266 OS << "Call graph node for function: '" << F->getName() <<"'\n";
268 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
270 for (const_iterator I = begin(), E = end(); I != E; ++I)
271 if (I->second->getFunction())
272 OS << " Calls function '" << I->second->getFunction()->getName() <<"'\n";
274 OS << " Calls external node\n";
278 void CallGraphNode::dump() const { print(llvm_cerr); }
280 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
281 for (unsigned i = CalledFunctions.size(); ; --i) {
282 assert(i && "Cannot find callee to remove!");
283 if (CalledFunctions[i-1].second == Callee) {
284 CalledFunctions.erase(CalledFunctions.begin()+i-1);
290 // removeAnyCallEdgeTo - This method removes any call edges from this node to
291 // the specified callee function. This takes more time to execute than
292 // removeCallEdgeTo, so it should not be used unless necessary.
293 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
294 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
295 if (CalledFunctions[i].second == Callee) {
296 CalledFunctions[i] = CalledFunctions.back();
297 CalledFunctions.pop_back();
302 // Enuse that users of CallGraph.h also link with this file
303 DEFINING_FILE_FOR(CallGraph)