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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/ADT/STLExtras.h"
12 : #include "llvm/ADT/SmallVector.h"
13 : #include "llvm/Config/llvm-config.h"
14 : #include "llvm/IR/CallSite.h"
15 : #include "llvm/IR/Module.h"
16 : #include "llvm/IR/Function.h"
17 : #include "llvm/IR/Intrinsics.h"
18 : #include "llvm/IR/PassManager.h"
19 : #include "llvm/Pass.h"
20 : #include "llvm/Support/Compiler.h"
21 : #include "llvm/Support/Debug.h"
22 : #include "llvm/Support/raw_ostream.h"
23 : #include <algorithm>
24 : #include <cassert>
25 :
26 : using namespace llvm;
27 :
28 : //===----------------------------------------------------------------------===//
29 : // Implementations of the CallGraph class methods.
30 : //
31 :
32 23930 : CallGraph::CallGraph(Module &M)
33 23930 : : M(M), ExternalCallingNode(getOrInsertFunction(nullptr)),
34 23930 : CallsExternalNode(llvm::make_unique<CallGraphNode>(nullptr)) {
35 : // Add every function to the call graph.
36 1067215 : for (Function &F : M)
37 1043285 : addToCallGraph(&F);
38 23930 : }
39 :
40 258 : CallGraph::CallGraph(CallGraph &&Arg)
41 258 : : M(Arg.M), FunctionMap(std::move(Arg.FunctionMap)),
42 258 : ExternalCallingNode(Arg.ExternalCallingNode),
43 516 : CallsExternalNode(std::move(Arg.CallsExternalNode)) {
44 : Arg.FunctionMap.clear();
45 258 : Arg.ExternalCallingNode = nullptr;
46 258 : }
47 :
48 48100 : CallGraph::~CallGraph() {
49 : // CallsExternalNode is not in the function map, delete it explicitly.
50 24179 : if (CallsExternalNode)
51 : CallsExternalNode->allReferencesDropped();
52 :
53 : // Reset all node's use counts to zero before deleting them to prevent an
54 : // assertion from firing.
55 : #ifndef NDEBUG
56 : for (auto &I : FunctionMap)
57 : I.second->allReferencesDropped();
58 : #endif
59 24179 : }
60 :
61 1043285 : void CallGraph::addToCallGraph(Function *F) {
62 1043285 : CallGraphNode *Node = getOrInsertFunction(F);
63 :
64 : // If this function has external linkage or has its address taken, anything
65 : // could call it.
66 54450 : if (!F->hasLocalLinkage() || F->hasAddressTaken())
67 1006910 : ExternalCallingNode->addCalledFunction(CallSite(), Node);
68 :
69 : // If this function is not defined in this translation unit, it could call
70 : // anything.
71 1043285 : if (F->isDeclaration() && !F->isIntrinsic())
72 105968 : Node->addCalledFunction(CallSite(), CallsExternalNode.get());
73 :
74 : // Look for calls by this function.
75 4580308 : for (BasicBlock &BB : *F)
76 27509372 : for (Instruction &I : BB) {
77 23972349 : if (auto CS = CallSite(&I)) {
78 : const Function *Callee = CS.getCalledFunction();
79 3800809 : if (!Callee || !Intrinsic::isLeaf(Callee->getIntrinsicID()))
80 : // Indirect calls of intrinsics are not allowed so no need to check.
81 : // We can be more precise here by using TargetArg returned by
82 : // Intrinsic::isLeaf.
83 41759 : Node->addCalledFunction(CS, CallsExternalNode.get());
84 3800795 : else if (!Callee->isIntrinsic())
85 6067580 : Node->addCalledFunction(CS, getOrInsertFunction(Callee));
86 : }
87 : }
88 1043285 : }
89 :
90 6 : void CallGraph::print(raw_ostream &OS) const {
91 : // Print in a deterministic order by sorting CallGraphNodes by name. We do
92 : // this here to avoid slowing down the non-printing fast path.
93 :
94 : SmallVector<CallGraphNode *, 16> Nodes;
95 : Nodes.reserve(FunctionMap.size());
96 :
97 25 : for (const auto &I : *this)
98 19 : Nodes.push_back(I.second.get());
99 :
100 : llvm::sort(Nodes, [](CallGraphNode *LHS, CallGraphNode *RHS) {
101 : if (Function *LF = LHS->getFunction())
102 : if (Function *RF = RHS->getFunction())
103 : return LF->getName() < RF->getName();
104 :
105 : return RHS->getFunction() != nullptr;
106 : });
107 :
108 25 : for (CallGraphNode *CN : Nodes)
109 19 : CN->print(OS);
110 6 : }
111 :
112 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
113 : LLVM_DUMP_METHOD void CallGraph::dump() const { print(dbgs()); }
114 : #endif
115 :
116 : // removeFunctionFromModule - Unlink the function from this module, returning
117 : // it. Because this removes the function from the module, the call graph node
118 : // is destroyed. This is only valid if the function does not call any other
119 : // functions (ie, there are no edges in it's CGN). The easiest way to do this
120 : // is to dropAllReferences before calling this.
121 : //
122 527028 : Function *CallGraph::removeFunctionFromModule(CallGraphNode *CGN) {
123 : assert(CGN->empty() && "Cannot remove function from call "
124 : "graph if it references other functions!");
125 527028 : Function *F = CGN->getFunction(); // Get the function for the call graph node
126 527028 : FunctionMap.erase(F); // Remove the call graph node from the map
127 :
128 527028 : M.getFunctionList().remove(F);
129 527028 : return F;
130 : }
131 :
132 : /// spliceFunction - Replace the function represented by this node by another.
133 : /// This does not rescan the body of the function, so it is suitable when
134 : /// splicing the body of the old function to the new while also updating all
135 : /// callers from old to new.
136 0 : void CallGraph::spliceFunction(const Function *From, const Function *To) {
137 : assert(FunctionMap.count(From) && "No CallGraphNode for function!");
138 : assert(!FunctionMap.count(To) &&
139 : "Pointing CallGraphNode at a function that already exists");
140 : FunctionMapTy::iterator I = FunctionMap.find(From);
141 0 : I->second->F = const_cast<Function*>(To);
142 0 : FunctionMap[To] = std::move(I->second);
143 : FunctionMap.erase(I);
144 0 : }
145 :
146 : // getOrInsertFunction - This method is identical to calling operator[], but
147 : // it will insert a new CallGraphNode for the specified function if one does
148 : // not already exist.
149 4102909 : CallGraphNode *CallGraph::getOrInsertFunction(const Function *F) {
150 4102909 : auto &CGN = FunctionMap[F];
151 4102909 : if (CGN)
152 : return CGN.get();
153 :
154 : assert((!F || F->getParent() == &M) && "Function not in current module!");
155 1067438 : CGN = llvm::make_unique<CallGraphNode>(const_cast<Function *>(F));
156 1067438 : return CGN.get();
157 : }
158 :
159 : //===----------------------------------------------------------------------===//
160 : // Implementations of the CallGraphNode class methods.
161 : //
162 :
163 19 : void CallGraphNode::print(raw_ostream &OS) const {
164 19 : if (Function *F = getFunction())
165 13 : OS << "Call graph node for function: '" << F->getName() << "'";
166 : else
167 6 : OS << "Call graph node <<null function>>";
168 :
169 19 : OS << "<<" << this << ">> #uses=" << getNumReferences() << '\n';
170 :
171 36 : for (const auto &I : *this) {
172 17 : OS << " CS<" << I.first << "> calls ";
173 17 : if (Function *FI = I.second->getFunction())
174 14 : OS << "function '" << FI->getName() <<"'\n";
175 : else
176 3 : OS << "external node\n";
177 : }
178 : OS << '\n';
179 19 : }
180 :
181 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
182 : LLVM_DUMP_METHOD void CallGraphNode::dump() const { print(dbgs()); }
183 : #endif
184 :
185 : /// removeCallEdgeFor - This method removes the edge in the node for the
186 : /// specified call site. Note that this method takes linear time, so it
187 : /// should be used sparingly.
188 1399050 : void CallGraphNode::removeCallEdgeFor(CallSite CS) {
189 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
190 : assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
191 112850180 : if (I->first == CS.getInstruction()) {
192 1399050 : I->second->DropRef();
193 : *I = CalledFunctions.back();
194 1399050 : CalledFunctions.pop_back();
195 1399050 : return;
196 : }
197 : }
198 : }
199 :
200 : // removeAnyCallEdgeTo - This method removes any call edges from this node to
201 : // the specified callee function. This takes more time to execute than
202 : // removeCallEdgeTo, so it should not be used unless necessary.
203 505665 : void CallGraphNode::removeAnyCallEdgeTo(CallGraphNode *Callee) {
204 211337373 : for (unsigned i = 0, e = CalledFunctions.size(); i != e; ++i)
205 420652086 : if (CalledFunctions[i].second == Callee) {
206 : Callee->DropRef();
207 : CalledFunctions[i] = CalledFunctions.back();
208 505491 : CalledFunctions.pop_back();
209 505491 : --i; --e;
210 : }
211 505665 : }
212 :
213 : /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
214 : /// from this node to the specified callee function.
215 0 : void CallGraphNode::removeOneAbstractEdgeTo(CallGraphNode *Callee) {
216 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
217 : assert(I != CalledFunctions.end() && "Cannot find callee to remove!");
218 : CallRecord &CR = *I;
219 0 : if (CR.second == Callee && CR.first == nullptr) {
220 : Callee->DropRef();
221 : *I = CalledFunctions.back();
222 0 : CalledFunctions.pop_back();
223 0 : return;
224 : }
225 : }
226 : }
227 :
228 : /// replaceCallEdge - This method replaces the edge in the node for the
229 : /// specified call site with a new one. Note that this method takes linear
230 : /// time, so it should be used sparingly.
231 169 : void CallGraphNode::replaceCallEdge(CallSite CS,
232 : CallSite NewCS, CallGraphNode *NewNode){
233 : for (CalledFunctionsVector::iterator I = CalledFunctions.begin(); ; ++I) {
234 : assert(I != CalledFunctions.end() && "Cannot find callsite to remove!");
235 1163 : if (I->first == CS.getInstruction()) {
236 169 : I->second->DropRef();
237 : I->first = NewCS.getInstruction();
238 169 : I->second = NewNode;
239 : NewNode->AddRef();
240 169 : return;
241 : }
242 : }
243 : }
244 :
245 : // Provide an explicit template instantiation for the static ID.
246 : AnalysisKey CallGraphAnalysis::Key;
247 :
248 1 : PreservedAnalyses CallGraphPrinterPass::run(Module &M,
249 : ModuleAnalysisManager &AM) {
250 1 : AM.getResult<CallGraphAnalysis>(M).print(OS);
251 1 : return PreservedAnalyses::all();
252 : }
253 :
254 : //===----------------------------------------------------------------------===//
255 : // Out-of-line definitions of CallGraphAnalysis class members.
256 : //
257 :
258 : //===----------------------------------------------------------------------===//
259 : // Implementations of the CallGraphWrapperPass class methods.
260 : //
261 :
262 47642 : CallGraphWrapperPass::CallGraphWrapperPass() : ModulePass(ID) {
263 23821 : initializeCallGraphWrapperPassPass(*PassRegistry::getPassRegistry());
264 23821 : }
265 :
266 : CallGraphWrapperPass::~CallGraphWrapperPass() = default;
267 :
268 23821 : void CallGraphWrapperPass::getAnalysisUsage(AnalysisUsage &AU) const {
269 : AU.setPreservesAll();
270 23821 : }
271 :
272 23795 : bool CallGraphWrapperPass::runOnModule(Module &M) {
273 : // All the real work is done in the constructor for the CallGraph.
274 23795 : G.reset(new CallGraph(M));
275 23795 : return false;
276 : }
277 :
278 387429 : INITIALIZE_PASS(CallGraphWrapperPass, "basiccg", "CallGraph Construction",
279 : false, true)
280 :
281 : char CallGraphWrapperPass::ID = 0;
282 :
283 23786 : void CallGraphWrapperPass::releaseMemory() { G.reset(); }
284 :
285 5 : void CallGraphWrapperPass::print(raw_ostream &OS, const Module *) const {
286 5 : if (!G) {
287 0 : OS << "No call graph has been built!\n";
288 0 : return;
289 : }
290 :
291 : // Just delegate.
292 5 : G->print(OS);
293 : }
294 :
295 : #if !defined(NDEBUG) || defined(LLVM_ENABLE_DUMP)
296 : LLVM_DUMP_METHOD
297 : void CallGraphWrapperPass::dump() const { print(dbgs(), nullptr); }
298 : #endif
299 :
300 : namespace {
301 :
302 : struct CallGraphPrinterLegacyPass : public ModulePass {
303 : static char ID; // Pass ID, replacement for typeid
304 :
305 5 : CallGraphPrinterLegacyPass() : ModulePass(ID) {
306 5 : initializeCallGraphPrinterLegacyPassPass(*PassRegistry::getPassRegistry());
307 : }
308 :
309 5 : void getAnalysisUsage(AnalysisUsage &AU) const override {
310 : AU.setPreservesAll();
311 : AU.addRequiredTransitive<CallGraphWrapperPass>();
312 5 : }
313 :
314 5 : bool runOnModule(Module &M) override {
315 5 : getAnalysis<CallGraphWrapperPass>().print(errs(), &M);
316 5 : return false;
317 : }
318 : };
319 :
320 : } // end anonymous namespace
321 :
322 : char CallGraphPrinterLegacyPass::ID = 0;
323 :
324 10756 : INITIALIZE_PASS_BEGIN(CallGraphPrinterLegacyPass, "print-callgraph",
325 : "Print a call graph", true, true)
326 10756 : INITIALIZE_PASS_DEPENDENCY(CallGraphWrapperPass)
327 21517 : INITIALIZE_PASS_END(CallGraphPrinterLegacyPass, "print-callgraph",
328 : "Print a call graph", true, true)
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