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/IntrinsicInst.h"
19 #include "llvm/Support/CallSite.h"
20 #include "llvm/Support/Debug.h"
21 #include "llvm/Support/raw_ostream.h"
26 //===----------------------------------------------------------------------===//
27 // BasicCallGraph class definition
29 class BasicCallGraph : public ModulePass, public CallGraph {
30 // Root is root of the call graph, or the external node if a 'main' function
35 // ExternalCallingNode - This node has edges to all external functions and
36 // those internal functions that have their address taken.
37 CallGraphNode *ExternalCallingNode;
39 // CallsExternalNode - This node has edges to it from all functions making
40 // indirect calls or calling an external function.
41 CallGraphNode *CallsExternalNode;
44 static char ID; // Class identification, replacement for typeinfo
45 BasicCallGraph() : ModulePass(ID), Root(0),
46 ExternalCallingNode(0), CallsExternalNode(0) {
47 initializeBasicCallGraphPass(*PassRegistry::getPassRegistry());
50 // runOnModule - Compute the call graph for the specified module.
51 virtual bool runOnModule(Module &M) {
52 CallGraph::initialize(M);
54 ExternalCallingNode = getOrInsertFunction(0);
55 CallsExternalNode = new CallGraphNode(0);
58 // Add every function to the call graph.
59 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
62 // If we didn't find a main function, use the external call graph node
63 if (Root == 0) Root = ExternalCallingNode;
68 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
72 virtual void print(raw_ostream &OS, const Module *) const {
73 OS << "CallGraph Root is: ";
74 if (Function *F = getRoot()->getFunction())
75 OS << F->getName() << "\n";
77 OS << "<<null function: 0x" << getRoot() << ">>\n";
80 CallGraph::print(OS, 0);
83 virtual void releaseMemory() {
87 /// getAdjustedAnalysisPointer - This method is used when a pass implements
88 /// an analysis interface through multiple inheritance. If needed, it should
89 /// override this to adjust the this pointer as needed for the specified pass
91 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
92 if (PI == &CallGraph::ID)
93 return (CallGraph*)this;
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->hasLocalLinkage()) {
119 ExternalCallingNode->addCalledFunction(CallSite(), 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 has its address taken, anything could call it.
131 if (F->hasAddressTaken())
132 ExternalCallingNode->addCalledFunction(CallSite(), Node);
134 // If this function is not defined in this translation unit, it could call
136 if (F->isDeclaration() && !F->isIntrinsic())
137 Node->addCalledFunction(CallSite(), CallsExternalNode);
139 // Look for calls by this function.
140 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
141 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
143 CallSite CS(cast<Value>(II));
144 if (CS && !isa<IntrinsicInst>(II)) {
145 const Function *Callee = CS.getCalledFunction();
147 Node->addCalledFunction(CS, getOrInsertFunction(Callee));
149 Node->addCalledFunction(CS, CallsExternalNode);
155 // destroy - Release memory for the call graph
156 virtual void destroy() {
157 /// CallsExternalNode is not in the function map, delete it explicitly.
158 if (CallsExternalNode) {
159 CallsExternalNode->allReferencesDropped();
160 delete CallsExternalNode;
161 CallsExternalNode = 0;
163 CallGraph::destroy();
167 } //End anonymous namespace
169 INITIALIZE_ANALYSIS_GROUP(CallGraph, "Call Graph", BasicCallGraph)
170 INITIALIZE_AG_PASS(BasicCallGraph, CallGraph, "basiccg",
171 "Basic CallGraph Construction", false, true, true)
173 char CallGraph::ID = 0;
174 char BasicCallGraph::ID = 0;
176 void CallGraph::initialize(Module &M) {
180 void CallGraph::destroy() {
181 if (FunctionMap.empty()) return;
183 // Reset all node's use counts to zero before deleting them to prevent an
184 // assertion from firing.
186 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
188 I->second->allReferencesDropped();
191 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
197 void CallGraph::print(raw_ostream &OS, Module*) const {
198 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
199 I->second->print(OS);
201 void CallGraph::dump() const {
205 //===----------------------------------------------------------------------===//
206 // Implementations of public modification methods
209 // removeFunctionFromModule - Unlink the function from this module, returning
210 // it. Because this removes the function from the module, the call graph node
211 // is destroyed. This is only valid if the function does not call any other
212 // functions (ie, there are no edges in it's CGN). The easiest way to do this
213 // is to dropAllReferences before calling this.
215 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
216 assert(CGN->empty() && "Cannot remove function from call "
217 "graph if it references other functions!");
218 Function *F = CGN->getFunction(); // Get the function for the call graph node
219 delete CGN; // Delete the call graph node for this func
220 FunctionMap.erase(F); // Remove the call graph node from the map
222 Mod->getFunctionList().remove(F);
226 /// spliceFunction - Replace the function represented by this node by another.
227 /// This does not rescan the body of the function, so it is suitable when
228 /// splicing the body of the old function to the new while also updating all
229 /// callers from old to new.
231 void CallGraph::spliceFunction(const Function *From, const Function *To) {
232 assert(FunctionMap.count(From) && "No CallGraphNode for function!");
233 assert(!FunctionMap.count(To) &&
234 "Pointing CallGraphNode at a function that already exists");
235 FunctionMapTy::iterator I = FunctionMap.find(From);
236 I->second->F = const_cast<Function*>(To);
237 FunctionMap[To] = I->second;
238 FunctionMap.erase(I);
241 // getOrInsertFunction - This method is identical to calling operator[], but
242 // it will insert a new CallGraphNode for the specified function if one does
243 // not already exist.
244 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
245 CallGraphNode *&CGN = FunctionMap[F];
248 assert((!F || F->getParent() == Mod) && "Function not in current module!");
249 return CGN = new CallGraphNode(const_cast<Function*>(F));
252 void CallGraphNode::print(raw_ostream &OS) const {
253 if (Function *F = getFunction())
254 OS << "Call graph node for function: '" << F->getName() << "'";
256 OS << "Call graph node <<null function>>";
258 OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
260 for (const_iterator I = begin(), E = end(); I != E; ++I) {
261 OS << " CS<" << I->first << "> calls ";
262 if (Function *FI = I->second->getFunction())
263 OS << "function '" << FI->getName() <<"'\n";
265 OS << "external node\n";
270 void CallGraphNode::dump() const { print(dbgs()); }
272 /// removeCallEdgeFor - This method removes the edge in the node for the
273 /// specified call site. Note that this method takes linear time, so it
274 /// should be used sparingly.
275 void CallGraphNode::removeCallEdgeFor(CallSite CS) {
276 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
277 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
278 if (I->first == CS.getInstruction()) {
279 I->second->DropRef();
280 *I = CalledFunctions.back();
281 CalledFunctions.pop_back();
287 // removeAnyCallEdgeTo - This method removes any call edges from this node to
288 // the specified callee function. This takes more time to execute than
289 // removeCallEdgeTo, so it should not be used unless necessary.
290 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
291 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
292 if (CalledFunctions[i].second == Callee) {
294 CalledFunctions[i] = CalledFunctions.back();
295 CalledFunctions.pop_back();
300 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
301 /// from this node to the specified callee function.
302 void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
303 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
304 assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
306 if (CR.second == Callee && CR.first == 0) {
308 *I = CalledFunctions.back();
309 CalledFunctions.pop_back();
315 /// replaceCallEdge - This method replaces the edge in the node for the
316 /// specified call site with a new one. Note that this method takes linear
317 /// time, so it should be used sparingly.
318 void CallGraphNode::replaceCallEdge(CallSite CS,
319 CallSite NewCS, CallGraphNode *NewNode){
320 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
321 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
322 if (I->first == CS.getInstruction()) {
323 I->second->DropRef();
324 I->first = NewCS.getInstruction();
332 // Enuse that users of CallGraph.h also link with this file
333 DEFINING_FILE_FOR(CallGraph)