Line data Source code
1 : //===- CallGraph.cpp - Build a Module's call graph ------------------------===//
2 : //
3 : // The LLVM Compiler Infrastructure
4 : //
5 : // This file is distributed under the University of Illinois Open Source
6 : // License. See LICENSE.TXT for details.
7 : //
8 : //===----------------------------------------------------------------------===//
9 :
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"
17 : using namespace llvm;
18 :
19 : //===----------------------------------------------------------------------===//
20 : // Implementations of the CallGraph class methods.
21 : //
22 :
23 4646 : CallGraph::CallGraph(Module &M)
24 4646 : : M(M), Root(nullptr), ExternalCallingNode(getOrInsertFunction(nullptr)),
25 13938 : CallsExternalNode(llvm::make_unique<CallGraphNode>(nullptr)) {
26 : // Add every function to the call graph.
27 13938 : for (Function &F : M)
28 70363 : addToCallGraph(&F);
29 :
30 : // If we didn't find a main function, use the external call graph node
31 4646 : if (!Root)
32 4055 : Root = ExternalCallingNode;
33 4646 : }
34 :
35 0 : CallGraph::CallGraph(CallGraph &&Arg)
36 0 : : M(Arg.M), FunctionMap(std::move(Arg.FunctionMap)), Root(Arg.Root),
37 0 : ExternalCallingNode(Arg.ExternalCallingNode),
38 0 : CallsExternalNode(std::move(Arg.CallsExternalNode)) {
39 0 : Arg.FunctionMap.clear();
40 0 : Arg.Root = nullptr;
41 0 : Arg.ExternalCallingNode = nullptr;
42 0 : }
43 :
44 13938 : CallGraph::~CallGraph() {
45 : // CallsExternalNode is not in the function map, delete it explicitly.
46 9292 : if (CallsExternalNode)
47 4646 : CallsExternalNode->allReferencesDropped();
48 :
49 : // Reset all node's use counts to zero before deleting them to prevent an
50 : // assertion from firing.
51 : #ifndef NDEBUG
52 : for (auto &I : FunctionMap)
53 : I.second->allReferencesDropped();
54 : #endif
55 4646 : }
56 :
57 70363 : void CallGraph::addToCallGraph(Function *F) {
58 70363 : CallGraphNode *Node = getOrInsertFunction(F);
59 :
60 : // If this function has external linkage, anything could call it.
61 140726 : if (!F->hasLocalLinkage()) {
62 107532 : ExternalCallingNode->addCalledFunction(CallSite(), Node);
63 :
64 : // Found the entry point?
65 107532 : if (F->getName() == "main") {
66 591 : if (Root) // Found multiple external mains? Don't pick one.
67 0 : Root = ExternalCallingNode;
68 : else
69 591 : Root = Node; // Found a main, keep track of it!
70 : }
71 : }
72 :
73 : // If this function has its address taken, anything could call it.
74 70363 : if (F->hasAddressTaken())
75 6783 : ExternalCallingNode->addCalledFunction(CallSite(), Node);
76 :
77 : // If this function is not defined in this translation unit, it could call
78 : // anything.
79 70363 : if (F->isDeclaration() && !F->isIntrinsic())
80 25827 : Node->addCalledFunction(CallSite(), CallsExternalNode.get());
81 :
82 : // Look for calls by this function.
83 140726 : for (Function::iterator BB = F->begin(), BBE = F->end(); BB != BBE; ++BB)
84 204420 : for (BasicBlock::iterator II = BB->begin(), IE = BB->end(); II != IE;
85 : ++II) {
86 984796 : CallSite CS(cast<Value>(II));
87 492398 : if (CS) {
88 65689 : const Function *Callee = CS.getCalledFunction();
89 65689 : if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
90 : // Indirect calls of intrinsics are not allowed so no need to check.
91 : // We can be more precise here by using TargetArg returned by
92 : // Intrinsic::isLeaf.
93 5202 : Node->addCalledFunction(CS, CallsExternalNode.get());
94 63088 : else if (!Callee->isIntrinsic())
95 41481 : Node->addCalledFunction(CS, getOrInsertFunction(Callee));
96 : }
97 : }
98 70363 : }
99 :
100 5 : void CallGraph::print(raw_ostream &OS) const {
101 5 : OS << "CallGraph Root is: ";
102 10 : if (Function *F = Root->getFunction())
103 0 : OS << F->getName() << "\n";
104 : else {
105 5 : OS << "<<null function: 0x" << Root << ">>\n";
106 : }
107 :
108 : // Print in a deterministic order by sorting CallGraphNodes by name. We do
109 : // this here to avoid slowing down the non-printing fast path.
110 :
111 : SmallVector<CallGraphNode *, 16> Nodes;
112 10 : Nodes.reserve(FunctionMap.size());
113 :
114 10 : for (auto I = begin(), E = end(); I != E; ++I)
115 32 : Nodes.push_back(I->second.get());
116 :
117 5 : std::sort(Nodes.begin(), Nodes.end(),
118 33 : [](CallGraphNode *LHS, CallGraphNode *RHS) {
119 33 : if (Function *LF = LHS->getFunction())
120 33 : if (Function *RF = RHS->getFunction())
121 12 : return LF->getName() < RF->getName();
122 :
123 21 : return RHS->getFunction() != nullptr;
124 5 : });
125 :
126 21 : for (CallGraphNode *CN : Nodes)
127 16 : CN->print(OS);
128 5 : }
129 :
130 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
131 : void CallGraph::dump() const { print(dbgs()); }
132 : #endif
133 :
134 : // removeFunctionFromModule - Unlink the function from this module, returning
135 : // it. Because this removes the function from the module, the call graph node
136 : // is destroyed. This is only valid if the function does not call any other
137 : // functions (ie, there are no edges in it's CGN). The easiest way to do this
138 : // is to dropAllReferences before calling this.
139 : //
140 12685 : Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
141 : assert(CGN->empty() && "Cannot remove function from call "
142 : "graph if it references other functions!");
143 12685 : Function *F = CGN->getFunction(); // Get the function for the call graph node
144 25370 : FunctionMap.erase(F); // Remove the call graph node from the map
145 :
146 25370 : M.getFunctionList().remove(F);
147 12685 : return F;
148 : }
149 :
150 : /// spliceFunction - Replace the function represented by this node by another.
151 : /// This does not rescan the body of the function, so it is suitable when
152 : /// splicing the body of the old function to the new while also updating all
153 : /// callers from old to new.
154 : ///
155 0 : void CallGraph::spliceFunction(const Function *From, const Function *To) {
156 : assert(FunctionMap.count(From) && "No CallGraphNode for function!");
157 : assert(!FunctionMap.count(To) &&
158 : "Pointing CallGraphNode at a function that already exists");
159 0 : FunctionMapTy::iterator I = FunctionMap.find(From);
160 0 : I->second->F = const_cast<Function*>(To);
161 0 : FunctionMap[To] = std::move(I->second);
162 0 : FunctionMap.erase(I);
163 0 : }
164 :
165 : // getOrInsertFunction - This method is identical to calling operator[], but
166 : // it will insert a new CallGraphNode for the specified function if one does
167 : // not already exist.
168 116638 : CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
169 116638 : auto &CGN = FunctionMap[F];
170 116638 : if (CGN)
171 : return CGN.get();
172 :
173 : assert((!F || F->getParent() == &M) && "Function not in current module!");
174 225141 : CGN = llvm::make_unique<CallGraphNode>(const_cast<Function *>(F));
175 75047 : return CGN.get();
176 : }
177 :
178 : //===----------------------------------------------------------------------===//
179 : // Implementations of the CallGraphNode class methods.
180 : //
181 :
182 16 : void CallGraphNode::print(raw_ostream &OS) const {
183 16 : if (Function *F = getFunction())
184 11 : OS << "Call graph node for function: '" << F->getName() << "'";
185 : else
186 5 : OS << "Call graph node <<null function>>";
187 :
188 48 : OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
189 :
190 63 : for (const_iterator I = begin(), E = end(); I != E; ++I) {
191 30 : OS << " CS<" << I->first << "> calls ";
192 30 : if (Function *FI = I->second->getFunction())
193 12 : OS << "function '" << FI->getName() <<"'\n";
194 : else
195 3 : OS << "external node\n";
196 : }
197 : OS << '\n';
198 16 : }
199 :
200 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
201 : void CallGraphNode::dump() const { print(dbgs()); }
202 : #endif
203 :
204 : /// removeCallEdgeFor - This method removes the edge in the node for the
205 : /// specified call site. Note that this method takes linear time, so it
206 : /// should be used sparingly.
207 17015 : void CallGraphNode::removeCallEdgeFor(CallSite CS) {
208 34030 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
209 : assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
210 63387 : if (I->first == CS.getInstruction()) {
211 17015 : I->second->DropRef();
212 34030 : *I = CalledFunctions.back();
213 17015 : CalledFunctions.pop_back();
214 17015 : return;
215 : }
216 : }
217 : }
218 :
219 : // removeAnyCallEdgeTo - This method removes any call edges from this node to
220 : // the specified callee function. This takes more time to execute than
221 : // removeCallEdgeTo, so it should not be used unless necessary.
222 164 : void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
223 4277 : for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
224 7898 : if (CalledFunctions[i].second == Callee) {
225 157 : Callee->DropRef();
226 314 : CalledFunctions[i] = CalledFunctions.back();
227 157 : CalledFunctions.pop_back();
228 157 : --i; --e;
229 : }
230 164 : }
231 :
232 : /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
233 : /// from this node to the specified callee function.
234 0 : void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
235 0 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
236 : assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
237 0 : CallRecord &CR = *I;
238 0 : if (CR.second == Callee && CR.first == nullptr) {
239 0 : Callee->DropRef();
240 0 : *I = CalledFunctions.back();
241 0 : CalledFunctions.pop_back();
242 0 : return;
243 : }
244 : }
245 : }
246 :
247 : /// replaceCallEdge - This method replaces the edge in the node for the
248 : /// specified call site with a new one. Note that this method takes linear
249 : /// time, so it should be used sparingly.
250 49 : void CallGraphNode::replaceCallEdge(CallSite CS,
251 : CallSite NewCS, CallGraphNode *NewNode){
252 98 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
253 : assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
254 303 : if (I->first == CS.getInstruction()) {
255 98 : I->second->DropRef();
256 98 : I->first = NewCS.getInstruction();
257 49 : I->second = NewNode;
258 49 : NewNode->AddRef();
259 49 : return;
260 : }
261 : }
262 : }
263 :
264 : //===----------------------------------------------------------------------===//
265 : // Out-of-line definitions of CallGraphAnalysis class members.
266 : //
267 :
268 : char CallGraphAnalysis::PassID;
269 :
270 : //===----------------------------------------------------------------------===//
271 : // Implementations of the CallGraphWrapperPass class methods.
272 : //
273 :
274 9288 : CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) {
275 4644 : initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry());
276 4644 : }
277 :
278 9260 : CallGraphWrapperPass::~CallGraphWrapperPass() {}
279 :
280 4644 : void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
281 4644 : AU.setPreservesAll();
282 4644 : }
283 :
284 4644 : bool CallGraphWrapperPass::runOnModule(Module &M) {
285 : // All the real work is done in the constructor for the CallGraph.
286 4644 : G.reset(new CallGraph(M));
287 4644 : return false;
288 : }
289 :
290 54190 : INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction",
291 : false, true)
292 :
293 : char CallGraphWrapperPass::ID = 0;
294 :
295 4645 : void CallGraphWrapperPass::releaseMemory() { G.reset(); }
296 :
297 5 : void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const {
298 10 : if (!G) {
299 0 : OS << "No call graph has been built!\n";
300 0 : return;
301 : }
302 :
303 : // Just delegate.
304 10 : G->print(OS);
305 : }
306 :
307 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
308 : void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); }
309 : #endif
|
