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/Compiler.h"
20 #include "llvm/Support/Streams.h"
24 /// isOnlyADirectCall - Return true if this callsite is *just* a direct call to
25 /// the specified function. Specifically return false if the callsite also
26 /// takes the address of the function.
27 static bool isOnlyADirectCall(Function *F, CallSite CS) {
28 if (!CS.getInstruction()) return false;
29 for (CallSite::arg_iterator I = CS.arg_begin(), E = CS.arg_end(); I != E; ++I)
30 if (*I == F) return false;
36 //===----------------------------------------------------------------------===//
37 // BasicCallGraph class definition
39 class VISIBILITY_HIDDEN BasicCallGraph : public CallGraph, public ModulePass {
40 // Root is root of the call graph, or the external node if a 'main' function
45 // ExternalCallingNode - This node has edges to all external functions and
46 // those internal functions that have their address taken.
47 CallGraphNode *ExternalCallingNode;
49 // CallsExternalNode - This node has edges to it from all functions making
50 // indirect calls or calling an external function.
51 CallGraphNode *CallsExternalNode;
54 BasicCallGraph() : Root(0), ExternalCallingNode(0), CallsExternalNode(0) {}
56 // runOnModule - Compute the call graph for the specified module.
57 virtual bool runOnModule(Module &M) {
58 CallGraph::initialize(M);
60 ExternalCallingNode = getOrInsertFunction(0);
61 CallsExternalNode = new CallGraphNode(0);
64 // Add every function to the call graph...
65 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
68 // If we didn't find a main function, use the external call graph node
69 if (Root == 0) Root = ExternalCallingNode;
74 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
78 void print(std::ostream *o, const Module *M) const {
82 virtual void print(std::ostream &o, const Module *M) const {
83 o << "CallGraph Root is: ";
84 if (Function *F = getRoot()->getFunction())
85 o << F->getName() << "\n";
87 o << "<<null function: 0x" << getRoot() << ">>\n";
89 CallGraph::print(o, M);
92 virtual void releaseMemory() {
96 /// dump - Print out this call graph.
98 inline void dump() const {
102 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
103 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
105 // getRoot - Return the root of the call graph, which is either main, or if
106 // main cannot be found, the external node.
108 CallGraphNode *getRoot() { return Root; }
109 const CallGraphNode *getRoot() const { return Root; }
112 //===---------------------------------------------------------------------
113 // Implementation of CallGraph construction
116 // addToCallGraph - Add a function to the call graph, and link the node to all
117 // of the functions that it calls.
119 void addToCallGraph(Function *F) {
120 CallGraphNode *Node = getOrInsertFunction(F);
122 // If this function has external linkage, anything could call it.
123 if (!F->hasInternalLinkage()) {
124 ExternalCallingNode->addCalledFunction(CallSite(), Node);
126 // Found the entry point?
127 if (F->getName() == "main") {
128 if (Root) // Found multiple external mains? Don't pick one.
129 Root = ExternalCallingNode;
131 Root = Node; // Found a main, keep track of it!
135 // If this function is not defined in this translation unit, it could call
137 if (F->isDeclaration() && !F->getIntrinsicID())
138 Node->addCalledFunction(CallSite(), CallsExternalNode);
140 // Loop over all of the users of the function... looking for callers...
142 bool isUsedExternally = false;
143 for (Value::use_iterator I = F->use_begin(), E = F->use_end(); I != E; ++I){
144 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
145 CallSite CS = CallSite::get(Inst);
146 if (isOnlyADirectCall(F, CS))
147 getOrInsertFunction(Inst->getParent()->getParent())
148 ->addCalledFunction(CS, Node);
150 isUsedExternally = true;
151 } else if (GlobalValue *GV = dyn_cast<GlobalValue>(*I)) {
152 for (Value::use_iterator I = GV->use_begin(), E = GV->use_end();
154 if (Instruction *Inst = dyn_cast<Instruction>(*I)) {
155 CallSite CS = CallSite::get(Inst);
156 if (isOnlyADirectCall(F, CS))
157 getOrInsertFunction(Inst->getParent()->getParent())
158 ->addCalledFunction(CS, Node);
160 isUsedExternally = true;
162 isUsedExternally = true;
164 } else { // Can't classify the user!
165 isUsedExternally = true;
168 if (isUsedExternally)
169 ExternalCallingNode->addCalledFunction(CallSite(), Node);
171 // Look for an indirect function call.
172 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
173 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
175 CallSite CS = CallSite::get(II);
176 if (CS.getInstruction() && !CS.getCalledFunction())
177 Node->addCalledFunction(CS, CallsExternalNode);
182 // destroy - Release memory for the call graph
183 virtual void destroy() {
184 /// CallsExternalNode is not in the function map, delete it explicitly.
185 delete CallsExternalNode;
186 CallsExternalNode = 0;
187 CallGraph::destroy();
191 RegisterAnalysisGroup<CallGraph> X("Call Graph");
192 RegisterPass<BasicCallGraph> Y("basiccg", "Basic CallGraph Construction");
193 RegisterAnalysisGroup<CallGraph, true> Z(Y);
195 } //End anonymous namespace
197 void CallGraph::initialize(Module &M) {
201 void CallGraph::destroy() {
202 if (!FunctionMap.empty()) {
203 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
210 void CallGraph::print(std::ostream &OS, const Module *M) const {
211 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
212 I->second->print(OS);
215 void CallGraph::dump() const {
219 //===----------------------------------------------------------------------===//
220 // Implementations of public modification methods
223 // removeFunctionFromModule - Unlink the function from this module, returning
224 // it. Because this removes the function from the module, the call graph node
225 // is destroyed. This is only valid if the function does not call any other
226 // functions (ie, there are no edges in it's CGN). The easiest way to do this
227 // is to dropAllReferences before calling this.
229 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
230 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
231 "graph if it references other functions!");
232 Function *F = CGN->getFunction(); // Get the function for the call graph node
233 delete CGN; // Delete the call graph node for this func
234 FunctionMap.erase(F); // Remove the call graph node from the map
236 Mod->getFunctionList().remove(F);
240 // changeFunction - This method changes the function associated with this
241 // CallGraphNode, for use by transformations that need to change the prototype
242 // of a Function (thus they must create a new Function and move the old code
244 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
245 iterator I = FunctionMap.find(OldF);
246 CallGraphNode *&New = FunctionMap[NewF];
247 assert(I != FunctionMap.end() && I->second && !New &&
248 "OldF didn't exist in CG or NewF already does!");
251 FunctionMap.erase(I);
254 // getOrInsertFunction - This method is identical to calling operator[], but
255 // it will insert a new CallGraphNode for the specified function if one does
256 // not already exist.
257 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
258 CallGraphNode *&CGN = FunctionMap[F];
261 assert((!F || F->getParent() == Mod) && "Function not in current module!");
262 return CGN = new CallGraphNode(const_cast<Function*>(F));
265 void CallGraphNode::print(std::ostream &OS) const {
266 if (Function *F = getFunction())
267 OS << "Call graph node for function: '" << F->getName() <<"'\n";
269 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
271 for (const_iterator I = begin(), E = end(); I != E; ++I)
272 if (I->second->getFunction())
273 OS << " Calls function '" << I->second->getFunction()->getName() <<"'\n";
275 OS << " Calls external node\n";
279 void CallGraphNode::dump() const { print(cerr); }
281 void CallGraphNode::removeCallEdgeTo(CallGraphNode *Callee) {
282 for (unsigned i = CalledFunctions.size(); ; --i) {
283 assert(i && "Cannot find callee to remove!");
284 if (CalledFunctions[i-1].second == Callee) {
285 CalledFunctions.erase(CalledFunctions.begin()+i-1);
291 // removeAnyCallEdgeTo - This method removes any call edges from this node to
292 // the specified callee function. This takes more time to execute than
293 // removeCallEdgeTo, so it should not be used unless necessary.
294 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
295 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
296 if (CalledFunctions[i].second == Callee) {
297 CalledFunctions[i] = CalledFunctions.back();
298 CalledFunctions.pop_back();
303 // Enuse that users of CallGraph.h also link with this file
304 DEFINING_FILE_FOR(CallGraph)