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/IR/Instructions.h"
17 #include "llvm/IR/IntrinsicInst.h"
18 #include "llvm/IR/Module.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());
53 // runOnModule - Compute the call graph for the specified module.
54 virtual bool runOnModule(Module &M) {
55 CallGraph::initialize(M);
57 ExternalCallingNode = getOrInsertFunction(0);
58 assert(!CallsExternalNode);
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 virtual void print(raw_ostream &OS, const Module *) const {
77 OS << "CallGraph Root is: ";
78 if (Function *F = getRoot()->getFunction())
79 OS << F->getName() << "\n";
81 OS << "<<null function: 0x" << getRoot() << ">>\n";
84 CallGraph::print(OS, 0);
87 virtual void releaseMemory() {
91 /// getAdjustedAnalysisPointer - This method is used when a pass implements
92 /// an analysis interface through multiple inheritance. If needed, it should
93 /// override this to adjust the this pointer as needed for the specified pass
95 virtual void *getAdjustedAnalysisPointer(AnalysisID PI) {
96 if (PI == &CallGraph::ID)
97 return (CallGraph*)this;
101 CallGraphNode* getExternalCallingNode() const { return ExternalCallingNode; }
102 CallGraphNode* getCallsExternalNode() const { return CallsExternalNode; }
104 // getRoot - Return the root of the call graph, which is either main, or if
105 // main cannot be found, the external node.
107 CallGraphNode *getRoot() { return Root; }
108 const CallGraphNode *getRoot() const { return Root; }
111 //===---------------------------------------------------------------------
112 // Implementation of CallGraph construction
115 // addToCallGraph - Add a function to the call graph, and link the node to all
116 // of the functions that it calls.
118 void addToCallGraph(Function *F) {
119 CallGraphNode *Node = getOrInsertFunction(F);
121 // If this function has external linkage, anything could call it.
122 if (!F->hasLocalLinkage()) {
123 ExternalCallingNode->addCalledFunction(CallSite(), Node);
125 // Found the entry point?
126 if (F->getName() == "main") {
127 if (Root) // Found multiple external mains? Don't pick one.
128 Root = ExternalCallingNode;
130 Root = Node; // Found a main, keep track of it!
134 // If this function has its address taken, anything could call it.
135 if (F->hasAddressTaken())
136 ExternalCallingNode->addCalledFunction(CallSite(), Node);
138 // If this function is not defined in this translation unit, it could call
140 if (F->isDeclaration() && !F->isIntrinsic())
141 Node->addCalledFunction(CallSite(), CallsExternalNode);
143 // Look for calls by this function.
144 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
145 for (BasicBlock::iterator II = BB->begin(), IE = BB->end();
147 CallSite CS(cast<Value>(II));
149 const Function *Callee = CS.getCalledFunction();
151 // Indirect calls of intrinsics are not allowed so no need to check.
152 Node->addCalledFunction(CS, CallsExternalNode);
153 else if (!Callee->isIntrinsic())
154 Node->addCalledFunction(CS, getOrInsertFunction(Callee));
160 // destroy - Release memory for the call graph
161 virtual void destroy() {
162 /// CallsExternalNode is not in the function map, delete it explicitly.
163 if (CallsExternalNode) {
164 CallsExternalNode->allReferencesDropped();
165 delete CallsExternalNode;
166 CallsExternalNode = 0;
168 CallGraph::destroy();
172 } //End anonymous namespace
174 INITIALIZE_ANALYSIS_GROUP(CallGraph, "Call Graph", BasicCallGraph)
175 INITIALIZE_AG_PASS(BasicCallGraph, CallGraph, "basiccg",
176 "Basic CallGraph Construction", false, true, true)
178 char CallGraph::ID = 0;
179 char BasicCallGraph::ID = 0;
181 void CallGraph::initialize(Module &M) {
185 void CallGraph::destroy() {
186 if (FunctionMap.empty()) return;
188 // Reset all node's use counts to zero before deleting them to prevent an
189 // assertion from firing.
191 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
193 I->second->allReferencesDropped();
196 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
202 void CallGraph::print(raw_ostream &OS, Module*) const {
203 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
204 I->second->print(OS);
206 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
207 void CallGraph::dump() const {
212 //===----------------------------------------------------------------------===//
213 // Implementations of public modification methods
216 // removeFunctionFromModule - Unlink the function from this module, returning
217 // it. Because this removes the function from the module, the call graph node
218 // is destroyed. This is only valid if the function does not call any other
219 // functions (ie, there are no edges in it's CGN). The easiest way to do this
220 // is to dropAllReferences before calling this.
222 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
223 assert(CGN->empty() && "Cannot remove function from call "
224 "graph if it references other functions!");
225 Function *F = CGN->getFunction(); // Get the function for the call graph node
226 delete CGN; // Delete the call graph node for this func
227 FunctionMap.erase(F); // Remove the call graph node from the map
229 Mod->getFunctionList().remove(F);
233 /// spliceFunction - Replace the function represented by this node by another.
234 /// This does not rescan the body of the function, so it is suitable when
235 /// splicing the body of the old function to the new while also updating all
236 /// callers from old to new.
238 void CallGraph::spliceFunction(const Function *From, const Function *To) {
239 assert(FunctionMap.count(From) && "No CallGraphNode for function!");
240 assert(!FunctionMap.count(To) &&
241 "Pointing CallGraphNode at a function that already exists");
242 FunctionMapTy::iterator I = FunctionMap.find(From);
243 I->second->F = const_cast<Function*>(To);
244 FunctionMap[To] = I->second;
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));
259 void CallGraphNode::print(raw_ostream &OS) const {
260 if (Function *F = getFunction())
261 OS << "Call graph node for function: '" << F->getName() << "'";
263 OS << "Call graph node <<null function>>";
265 OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
267 for (const_iterator I = begin(), E = end(); I != E; ++I) {
268 OS << " CS<" << I->first << "> calls ";
269 if (Function *FI = I->second->getFunction())
270 OS << "function '" << FI->getName() <<"'\n";
272 OS << "external node\n";
277 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
278 void CallGraphNode::dump() const { print(dbgs()); }
281 /// removeCallEdgeFor - This method removes the edge in the node for the
282 /// specified call site. Note that this method takes linear time, so it
283 /// should be used sparingly.
284 void CallGraphNode::removeCallEdgeFor(CallSite CS) {
285 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
286 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
287 if (I->first == CS.getInstruction()) {
288 I->second->DropRef();
289 *I = CalledFunctions.back();
290 CalledFunctions.pop_back();
296 // removeAnyCallEdgeTo - This method removes any call edges from this node to
297 // the specified callee function. This takes more time to execute than
298 // removeCallEdgeTo, so it should not be used unless necessary.
299 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
300 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
301 if (CalledFunctions[i].second == Callee) {
303 CalledFunctions[i] = CalledFunctions.back();
304 CalledFunctions.pop_back();
309 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
310 /// from this node to the specified callee function.
311 void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
312 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
313 assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
315 if (CR.second == Callee && CR.first == 0) {
317 *I = CalledFunctions.back();
318 CalledFunctions.pop_back();
324 /// replaceCallEdge - This method replaces the edge in the node for the
325 /// specified call site with a new one. Note that this method takes linear
326 /// time, so it should be used sparingly.
327 void CallGraphNode::replaceCallEdge(CallSite CS,
328 CallSite NewCS, CallGraphNode *NewNode){
329 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
330 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
331 if (I->first == CS.getInstruction()) {
332 I->second->DropRef();
333 I->first = NewCS.getInstruction();
341 // Enuse that users of CallGraph.h also link with this file
342 DEFINING_FILE_FOR(CallGraph)