1 //===- CallGraph.cpp - Build a Module's call graph ------------------------===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 return !CS.hasArgument(F);
34 //===----------------------------------------------------------------------===//
35 // BasicCallGraph class definition
37 class VISIBILITY_HIDDEN BasicCallGraph : public CallGraph, public ModulePass {
38 // Root is root of the call graph, or the external node if a 'main' function
43 // ExternalCallingNode - This node has edges to all external functions and
44 // those internal functions that have their address taken.
45 CallGraphNode *ExternalCallingNode;
47 // CallsExternalNode - This node has edges to it from all functions making
48 // indirect calls or calling an external function.
49 CallGraphNode *CallsExternalNode;
52 static char ID; // Class identification, replacement for typeinfo
53 BasicCallGraph() : ModulePass(&ID), Root(0),
54 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->isIntrinsic())
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 } //End anonymous namespace
193 static RegisterAnalysisGroup<CallGraph> X("Call Graph");
194 static RegisterPass<BasicCallGraph>
195 Y("basiccg", "Basic CallGraph Construction", false, true);
196 static RegisterAnalysisGroup<CallGraph, true> Z(Y);
198 char CallGraph::ID = 0;
199 char BasicCallGraph::ID = 0;
201 void CallGraph::initialize(Module &M) {
205 void CallGraph::destroy() {
206 if (!FunctionMap.empty()) {
207 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
214 void CallGraph::print(std::ostream &OS, const Module *M) const {
215 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
216 I->second->print(OS);
219 void CallGraph::dump() const {
223 //===----------------------------------------------------------------------===//
224 // Implementations of public modification methods
227 // removeFunctionFromModule - Unlink the function from this module, returning
228 // it. Because this removes the function from the module, the call graph node
229 // is destroyed. This is only valid if the function does not call any other
230 // functions (ie, there are no edges in it's CGN). The easiest way to do this
231 // is to dropAllReferences before calling this.
233 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
234 assert(CGN->CalledFunctions.empty() && "Cannot remove function from call "
235 "graph if it references other functions!");
236 Function *F = CGN->getFunction(); // Get the function for the call graph node
237 delete CGN; // Delete the call graph node for this func
238 FunctionMap.erase(F); // Remove the call graph node from the map
240 Mod->getFunctionList().remove(F);
244 // changeFunction - This method changes the function associated with this
245 // CallGraphNode, for use by transformations that need to change the prototype
246 // of a Function (thus they must create a new Function and move the old code
248 void CallGraph::changeFunction(Function *OldF, Function *NewF) {
249 iterator I = FunctionMap.find(OldF);
250 CallGraphNode *&New = FunctionMap[NewF];
251 assert(I != FunctionMap.end() && I->second && !New &&
252 "OldF didn't exist in CG or NewF already does!");
255 FunctionMap.erase(I);
258 // getOrInsertFunction - This method is identical to calling operator[], but
259 // it will insert a new CallGraphNode for the specified function if one does
260 // not already exist.
261 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
262 CallGraphNode *&CGN = FunctionMap[F];
265 assert((!F || F->getParent() == Mod) && "Function not in current module!");
266 return CGN = new CallGraphNode(const_cast<Function*>(F));
269 void CallGraphNode::print(std::ostream &OS) const {
270 if (Function *F = getFunction())
271 OS << "Call graph node for function: '" << F->getName() <<"'\n";
273 OS << "Call graph node <<null function: 0x" << this << ">>:\n";
275 for (const_iterator I = begin(), E = end(); I != E; ++I)
276 if (I->second->getFunction())
277 OS << " Calls function '" << I->second->getFunction()->getName() <<"'\n";
279 OS << " Calls external node\n";
283 void CallGraphNode::dump() const { print(cerr); }
285 /// removeCallEdgeFor - This method removes the edge in the node for the
286 /// specified call site. Note that this method takes linear time, so it
287 /// should be used sparingly.
288 void CallGraphNode::removeCallEdgeFor(CallSite CS) {
289 for (unsigned i = CalledFunctions.size(); ; --i) {
290 assert(i && "Cannot find callee to remove!");
291 if (CalledFunctions[i-1].first == CS) {
292 CalledFunctions.erase(CalledFunctions.begin()+i-1);
299 // removeAnyCallEdgeTo - This method removes any call edges from this node to
300 // the specified callee function. This takes more time to execute than
301 // removeCallEdgeTo, so it should not be used unless necessary.
302 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
303 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
304 if (CalledFunctions[i].second == Callee) {
305 CalledFunctions[i] = CalledFunctions.back();
306 CalledFunctions.pop_back();
311 // Enuse that users of CallGraph.h also link with this file
312 DEFINING_FILE_FOR(CallGraph)