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 #include "llvm/Analysis/CallGraph.h"
11 #include "llvm/IR/CallSite.h"
12 #include "llvm/IR/Instructions.h"
13 #include "llvm/IR/IntrinsicInst.h"
14 #include "llvm/IR/Module.h"
15 #include "llvm/Support/Debug.h"
16 #include "llvm/Support/raw_ostream.h"
19 //===----------------------------------------------------------------------===//
20 // Implementations of the CallGraph class methods.
23 CallGraph::CallGraph(Module &M)
24 : M(M), Root(nullptr), ExternalCallingNode(getOrInsertFunction(nullptr)),
25 CallsExternalNode(new CallGraphNode(nullptr)) {
26 // Add every function to the call graph.
27 for (Module::iterator I = M.begin(), E = M.end(); I != E; ++I)
30 // If we didn't find a main function, use the external call graph node
32 Root = ExternalCallingNode;
35 CallGraph::~CallGraph() {
36 // CallsExternalNode is not in the function map, delete it explicitly.
37 CallsExternalNode->allReferencesDropped();
38 delete CallsExternalNode;
40 // Reset all node's use counts to zero before deleting them to prevent an
41 // assertion from firing.
43 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
45 I->second->allReferencesDropped();
47 for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
52 void CallGraph::addToCallGraph(Function *F) {
53 CallGraphNode *Node = getOrInsertFunction(F);
55 // If this function has external linkage, anything could call it.
56 if (!F->hasLocalLinkage()) {
57 ExternalCallingNode->addCalledFunction(CallSite(), Node);
59 // Found the entry point?
60 if (F->getName() == "main") {
61 if (Root) // Found multiple external mains? Don't pick one.
62 Root = ExternalCallingNode;
64 Root = Node; // Found a main, keep track of it!
68 // If this function has its address taken, anything could call it.
69 if (F->hasAddressTaken())
70 ExternalCallingNode->addCalledFunction(CallSite(), Node);
72 // If this function is not defined in this translation unit, it could call
74 if (F->isDeclaration() && !F->isIntrinsic())
75 Node->addCalledFunction(CallSite(), CallsExternalNode);
77 // Look for calls by this function.
78 for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
79 for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;
81 CallSite CS(cast<Value>(II));
83 const Function *Callee = CS.getCalledFunction();
85 // Indirect calls of intrinsics are not allowed so no need to check.
86 Node->addCalledFunction(CS, CallsExternalNode);
87 else if (!Callee->isIntrinsic())
88 Node->addCalledFunction(CS, getOrInsertFunction(Callee));
93 void CallGraph::print(raw_ostream &OS) const {
94 OS << "CallGraph Root is: ";
95 if (Function *F = Root->getFunction())
96 OS << F->getName() << "\n";
98 OS << "<<null function: 0x" << Root << ">>\n";
101 for (CallGraph::const_iterator I = begin(), E = end(); I != E; ++I)
102 I->second->print(OS);
105 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
106 void CallGraph::dump() const { print(dbgs()); }
109 // removeFunctionFromModule - Unlink the function from this module, returning
110 // it. Because this removes the function from the module, the call graph node
111 // is destroyed. This is only valid if the function does not call any other
112 // functions (ie, there are no edges in it's CGN). The easiest way to do this
113 // is to dropAllReferences before calling this.
115 Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
116 assert(CGN->empty() && "Cannot remove function from call "
117 "graph if it references other functions!");
118 Function *F = CGN->getFunction(); // Get the function for the call graph node
119 delete CGN; // Delete the call graph node for this func
120 FunctionMap.erase(F); // Remove the call graph node from the map
122 M.getFunctionList().remove(F);
126 /// spliceFunction - Replace the function represented by this node by another.
127 /// This does not rescan the body of the function, so it is suitable when
128 /// splicing the body of the old function to the new while also updating all
129 /// callers from old to new.
131 void CallGraph::spliceFunction(const Function *From, const Function *To) {
132 assert(FunctionMap.count(From) && "No CallGraphNode for function!");
133 assert(!FunctionMap.count(To) &&
134 "Pointing CallGraphNode at a function that already exists");
135 FunctionMapTy::iterator I = FunctionMap.find(From);
136 I->second->F = const_cast<Function*>(To);
137 FunctionMap[To] = I->second;
138 FunctionMap.erase(I);
141 // getOrInsertFunction - This method is identical to calling operator[], but
142 // it will insert a new CallGraphNode for the specified function if one does
143 // not already exist.
144 CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
145 CallGraphNode *&CGN = FunctionMap[F];
149 assert((!F || F->getParent() == &M) && "Function not in current module!");
150 return CGN = new CallGraphNode(const_cast<Function*>(F));
153 //===----------------------------------------------------------------------===//
154 // Implementations of the CallGraphNode class methods.
157 void CallGraphNode::print(raw_ostream &OS) const {
158 if (Function *F = getFunction())
159 OS << "Call graph node for function: '" << F->getName() << "'";
161 OS << "Call graph node <<null function>>";
163 OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
165 for (const_iterator I = begin(), E = end(); I != E; ++I) {
166 OS << " CS<" << I->first << "> calls ";
167 if (Function *FI = I->second->getFunction())
168 OS << "function '" << FI->getName() <<"'\n";
170 OS << "external node\n";
175 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
176 void CallGraphNode::dump() const { print(dbgs()); }
179 /// removeCallEdgeFor - This method removes the edge in the node for the
180 /// specified call site. Note that this method takes linear time, so it
181 /// should be used sparingly.
182 void CallGraphNode::removeCallEdgeFor(CallSite CS) {
183 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
184 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
185 if (I->first == CS.getInstruction()) {
186 I->second->DropRef();
187 *I = CalledFunctions.back();
188 CalledFunctions.pop_back();
194 // removeAnyCallEdgeTo - This method removes any call edges from this node to
195 // the specified callee function. This takes more time to execute than
196 // removeCallEdgeTo, so it should not be used unless necessary.
197 void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
198 for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
199 if (CalledFunctions[i].second == Callee) {
201 CalledFunctions[i] = CalledFunctions.back();
202 CalledFunctions.pop_back();
207 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
208 /// from this node to the specified callee function.
209 void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
210 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
211 assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
213 if (CR.second == Callee && CR.first == nullptr) {
215 *I = CalledFunctions.back();
216 CalledFunctions.pop_back();
222 /// replaceCallEdge - This method replaces the edge in the node for the
223 /// specified call site with a new one. Note that this method takes linear
224 /// time, so it should be used sparingly.
225 void CallGraphNode::replaceCallEdge(CallSite CS,
226 CallSite NewCS, CallGraphNode *NewNode){
227 for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
228 assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
229 if (I->first == CS.getInstruction()) {
230 I->second->DropRef();
231 I->first = NewCS.getInstruction();
239 //===----------------------------------------------------------------------===//
240 // Out-of-line definitions of CallGraphAnalysis class members.
243 char CallGraphAnalysis::PassID;
245 //===----------------------------------------------------------------------===//
246 // Implementations of the CallGraphWrapperPass class methods.
249 CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) {
250 initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry());
253 CallGraphWrapperPass::~CallGraphWrapperPass() {}
255 void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
256 AU.setPreservesAll();
259 bool CallGraphWrapperPass::runOnModule(Module &M) {
260 // All the real work is done in the constructor for the CallGraph.
261 G.reset(new CallGraph(M));
265 INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction",
268 char CallGraphWrapperPass::ID = 0;
270 void CallGraphWrapperPass::releaseMemory() { G.reset(); }
272 void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const {
274 OS << "No call graph has been built!\n";
282 #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
283 void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); }