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 void llvm::BasicCallGraphStub() {}
24 static bool isOnlyADirectCall(Function *F, CallSite CS) {
25 if (!CS.getInstruction()) return false;
26 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
27 if (*I == F) return false;
33 //===----------------------------------------------------------------------===//
34 // BasicCallGraph class definition
36 class BasicCallGraph : public CallGraph, public ModulePass {
37 // Root is root of the call graph, or the external node if a 'main' function
42 // ExternalCallingNode - This node has edges to all external functions and
43 // those internal functions that have their address taken.
44 CallGraphNode *ExternalCallingNode;
46 // CallsExternalNode - This node has edges to it from all functions making
47 // indirect calls or calling an external function.
48 CallGraphNode *CallsExternalNode;
51 BasicCallGraph() : Root(0), ExternalCallingNode(0), CallsExternalNode(0) {}
52 ~BasicCallGraph() { destroy(); }
54 // runOnModule - Compute the call graph for the specified module.
55 virtual bool runOnModule(Module &M) {
57 CallGraph::initialize(M);
59 ExternalCallingNode = getOrInsertFunction(0);
60 CallsExternalNode = new CallGraphNode(0);
63 // Add every function to the call graph...
64 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
67 // If we didn't find a main function, use the external call graph node
68 if (Root == 0) Root = ExternalCallingNode;
73 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
77 virtual void print(std::ostream &o, const Module *M) const {
78 o << "CallGraph Root is: ";
79 if (Function *F = getRoot()->getFunction())
80 o << F->getName() << "\n";
82 o << "<<null function: 0x" << getRoot() << ">>\n";
84 CallGraph::print(o, M);
87 virtual void releaseMemory() {
91 /// dump - Print out this call graph.
93 inline void dump() const {
94 print(std::cerr, Mod);
97 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
98 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
100 // getRoot - Return the root of the call graph, which is either main, or if
101 // main cannot be found, the external node.
103 CallGraphNode *getRoot() { return Root; }
104 const CallGraphNode *getRoot() const { return Root; }
107 //===---------------------------------------------------------------------
108 // Implementation of CallGraph construction
111 // addToCallGraph - Add a function to the call graph, and link the node to all
112 // of the functions that it calls.
114 void addToCallGraph(Function *F) {
115 CallGraphNode *Node = getOrInsertFunction(F);
117 // If this function has external linkage, anything could call it...
118 if (!F->hasInternalLinkage()) {
119 ExternalCallingNode->addCalledFunction(Node);
121 // Found the entry point?
122 if (F->getName() == "main") {
123 if (Root) // Found multiple external mains? Don't pick one.
124 Root = ExternalCallingNode;
126 Root = Node; // Found a main, keep track of it!
130 // If this function is not defined in this translation unit, it could call
132 if (F->isExternal() && !F->getIntrinsicID())
133 Node->addCalledFunction(CallsExternalNode);
135 // Loop over all of the users of the function... looking for callers...
137 bool isUsedExternally = false;
138 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
139 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
140 if (isOnlyADirectCall(F, CallSite::get(Inst)))
141 getOrInsertFunction(Inst->getParent()->getParent())
142 ->addCalledFunction(Node);
144 isUsedExternally = true;
145 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
146 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
148 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
149 if (isOnlyADirectCall(F, CallSite::get(Inst)))
150 getOrInsertFunction(Inst->getParent()->getParent())
151 ->addCalledFunction(Node);
153 isUsedExternally = true;
155 isUsedExternally = true;
157 } else { // Can't classify the user!
158 isUsedExternally = true;
161 if (isUsedExternally)
162 ExternalCallingNode->addCalledFunction(Node);
164 // Look for an indirect function call...
165 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
166 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
168 CallSite CS = CallSite::get(II);
169 if (CS.getInstruction() && !CS.getCalledFunction())
170 Node->addCalledFunction(CallsExternalNode);
175 // destroy - Release memory for the call graph
176 virtual void destroy() {
177 if (!CallsExternalNode) {
178 delete CallsExternalNode;
179 CallsExternalNode = 0;
184 RegisterAnalysisGroup<CallGraph> X("Call Graph");
185 RegisterOpt<BasicCallGraph> Y("basiccg", "Basic CallGraph Construction");
186 RegisterAnalysisGroup<CallGraph, BasicCallGraph, true> Z;
188 } //End anonymous namespace
190 void CallGraph::initialize(Module &M) {
195 void CallGraph::destroy() {
196 if(!FunctionMap.size()) {
197 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
204 void CallGraph::print(std::ostream &OS, const Module *M) const {
205 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
206 I->second->print(OS);
209 void CallGraph::dump() const {
213 //===----------------------------------------------------------------------===//
214 // Implementations of public modification methods
217 // removeFunctionFromModule - Unlink the function from this module, returning
218 // it. Because this removes the function from the module, the call graph node
219 // is destroyed. This is only valid if the function does not call any other
220 // functions (ie, there are no edges in it's CGN). The easiest way to do this
221 // is to dropAllReferences before calling this.
223 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
224 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
225 "graph if it references other functions!");
226 Function *F = CGN->getFunction(); // Get the function for the call graph node
227 delete CGN; // Delete the call graph node for this func
228 FunctionMap.erase(F); // Remove the call graph node from the map
230 Mod->getFunctionList().remove(F);
234 // changeFunction - This method changes the function associated with this
235 // CallGraphNode, for use by transformations that need to change the prototype
236 // of a Function (thus they must create a new Function and move the old code
238 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
239 iterator I = FunctionMap.find(OldF);
240 CallGraphNode *&New = FunctionMap[NewF];
241 assert(I != FunctionMap.end() && I->second && !New &&
242 "OldF didn't exist in CG or NewF already does!");
245 FunctionMap.erase(I);
248 // getOrInsertFunction - This method is identical to calling operator[], but
249 // it will insert a new CallGraphNode for the specified function if one does
250 // not already exist.
251 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
252 CallGraphNode *&CGN = FunctionMap[F];
255 assert((!F || F->getParent() == Mod) && "Function not in current module!");
256 return CGN = new CallGraphNode(const_cast<Function*>(F));
261 int CallGraph::stub; // to ensure linkage of this file.
263 void CallGraphNode::print(std::ostream &OS) const {
264 if (Function *F = getFunction())
265 OS << "Call graph node for function: '" << F->getName() <<"'\n";
267 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
269 for (const_iterator I = begin(), E = end(); I != E; ++I)
270 if ((*I)->getFunction())
271 OS << " Calls function '" << (*I)->getFunction()->getName() << "'\n";
273 OS << " Calls external node\n";
277 void CallGraphNode::dump() const { print(std::cerr); }
279 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
280 for (unsigned i = CalledFunctions.size(); ; --i) {
281 assert(i && "Cannot find callee to remove!");
282 if (CalledFunctions[i-1] == Callee) {
283 CalledFunctions.erase(CalledFunctions.begin()+i-1);
289 // removeAnyCallEdgeTo - This method removes any call edges from this node to
290 // the specified callee function. This takes more time to execute than
291 // removeCallEdgeTo, so it should not be used unless necessary.
292 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
293 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
294 if (CalledFunctions[i] == Callee) {
295 CalledFunctions[i] = CalledFunctions.back();
296 CalledFunctions.pop_back();