1 //===- CallGraph.cpp - AST-based Call graph -------------------------------===//
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
7 //===----------------------------------------------------------------------===//
9 // This file defines the AST-based CallGraph.
11 //===----------------------------------------------------------------------===//
13 #include "clang/Analysis/CallGraph.h"
14 #include "clang/AST/Decl.h"
15 #include "clang/AST/DeclBase.h"
16 #include "clang/AST/DeclObjC.h"
17 #include "clang/AST/Expr.h"
18 #include "clang/AST/ExprObjC.h"
19 #include "clang/AST/Stmt.h"
20 #include "clang/AST/StmtVisitor.h"
21 #include "clang/Basic/IdentifierTable.h"
22 #include "clang/Basic/LLVM.h"
23 #include "llvm/ADT/PostOrderIterator.h"
24 #include "llvm/ADT/STLExtras.h"
25 #include "llvm/ADT/Statistic.h"
26 #include "llvm/Support/Casting.h"
27 #include "llvm/Support/Compiler.h"
28 #include "llvm/Support/DOTGraphTraits.h"
29 #include "llvm/Support/GraphWriter.h"
30 #include "llvm/Support/raw_ostream.h"
35 using namespace clang;
37 #define DEBUG_TYPE "CallGraph"
39 STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges");
40 STATISTIC(NumBlockCallEdges, "Number of block call edges");
44 /// A helper class, which walks the AST and locates all the call sites in the
45 /// given function body.
46 class CGBuilder : public StmtVisitor<CGBuilder> {
48 CallGraphNode *CallerNode;
51 CGBuilder(CallGraph *g, CallGraphNode *N) : G(g), CallerNode(N) {}
53 void VisitStmt(Stmt *S) { VisitChildren(S); }
55 Decl *getDeclFromCall(CallExpr *CE) {
56 if (FunctionDecl *CalleeDecl = CE->getDirectCallee())
59 // Simple detection of a call through a block.
60 Expr *CEE = CE->getCallee()->IgnoreParenImpCasts();
61 if (BlockExpr *Block = dyn_cast<BlockExpr>(CEE)) {
63 return Block->getBlockDecl();
69 void addCalledDecl(Decl *D) {
70 if (G->includeInGraph(D)) {
71 CallGraphNode *CalleeNode = G->getOrInsertNode(D);
72 CallerNode->addCallee(CalleeNode);
76 void VisitCallExpr(CallExpr *CE) {
77 if (Decl *D = getDeclFromCall(CE))
82 void VisitLambdaExpr(LambdaExpr *LE) {
83 if (FunctionTemplateDecl *FTD = LE->getDependentCallOperator())
84 for (FunctionDecl *FD : FTD->specializations())
85 G->VisitFunctionDecl(FD);
86 else if (CXXMethodDecl *MD = LE->getCallOperator())
87 G->VisitFunctionDecl(MD);
90 void VisitCXXNewExpr(CXXNewExpr *E) {
91 if (FunctionDecl *FD = E->getOperatorNew())
96 void VisitCXXConstructExpr(CXXConstructExpr *E) {
97 CXXConstructorDecl *Ctor = E->getConstructor();
98 if (FunctionDecl *Def = Ctor->getDefinition())
103 // Include the evaluation of the default argument.
104 void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
108 // Include the evaluation of the default initializers in a class.
109 void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
113 // Adds may-call edges for the ObjC message sends.
114 void VisitObjCMessageExpr(ObjCMessageExpr *ME) {
115 if (ObjCInterfaceDecl *IDecl = ME->getReceiverInterface()) {
116 Selector Sel = ME->getSelector();
118 // Find the callee definition within the same translation unit.
120 if (ME->isInstanceMessage())
121 D = IDecl->lookupPrivateMethod(Sel);
123 D = IDecl->lookupPrivateClassMethod(Sel);
131 void VisitChildren(Stmt *S) {
132 for (Stmt *SubStmt : S->children())
134 this->Visit(SubStmt);
140 void CallGraph::addNodesForBlocks(DeclContext *D) {
141 if (BlockDecl *BD = dyn_cast<BlockDecl>(D))
142 addNodeForDecl(BD, true);
144 for (auto *I : D->decls())
145 if (auto *DC = dyn_cast<DeclContext>(I))
146 addNodesForBlocks(DC);
149 CallGraph::CallGraph() {
150 Root = getOrInsertNode(nullptr);
153 CallGraph::~CallGraph() = default;
155 bool CallGraph::includeInGraph(const Decl *D) {
160 if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
161 // We skip function template definitions, as their semantics is
162 // only determined when they are instantiated.
163 if (FD->isDependentContext())
166 IdentifierInfo *II = FD->getIdentifier();
167 if (II && II->getName().startswith("__inline"))
174 void CallGraph::addNodeForDecl(Decl* D, bool IsGlobal) {
177 // Allocate a new node, mark it as root, and process its calls.
178 CallGraphNode *Node = getOrInsertNode(D);
180 // Process all the calls by this function as well.
181 CGBuilder builder(this, Node);
182 if (Stmt *Body = D->getBody())
185 // Include C++ constructor member initializers.
186 if (auto constructor = dyn_cast<CXXConstructorDecl>(D)) {
187 for (CXXCtorInitializer *init : constructor->inits()) {
188 builder.Visit(init->getInit());
193 CallGraphNode *CallGraph::getNode(const Decl *F) const {
194 FunctionMapTy::const_iterator I = FunctionMap.find(F);
195 if (I == FunctionMap.end()) return nullptr;
196 return I->second.get();
199 CallGraphNode *CallGraph::getOrInsertNode(Decl *F) {
200 if (F && !isa<ObjCMethodDecl>(F))
201 F = F->getCanonicalDecl();
203 std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];
207 Node = std::make_unique<CallGraphNode>(F);
208 // Make Root node a parent of all functions to make sure all are reachable.
210 Root->addCallee(Node.get());
214 void CallGraph::print(raw_ostream &OS) const {
215 OS << " --- Call graph Dump --- \n";
217 // We are going to print the graph in reverse post order, partially, to make
218 // sure the output is deterministic.
219 llvm::ReversePostOrderTraversal<const CallGraph *> RPOT(this);
220 for (llvm::ReversePostOrderTraversal<const CallGraph *>::rpo_iterator
221 I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
222 const CallGraphNode *N = *I;
231 for (CallGraphNode::const_iterator CI = N->begin(),
232 CE = N->end(); CI != CE; ++CI) {
233 assert(*CI != Root && "No one can call the root node.");
242 LLVM_DUMP_METHOD void CallGraph::dump() const {
246 void CallGraph::viewGraph() const {
247 llvm::ViewGraph(this, "CallGraph");
250 void CallGraphNode::print(raw_ostream &os) const {
251 if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(FD))
252 return ND->printQualifiedName(os);
256 LLVM_DUMP_METHOD void CallGraphNode::dump() const {
263 struct DOTGraphTraits<const CallGraph*> : public DefaultDOTGraphTraits {
264 DOTGraphTraits (bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
266 static std::string getNodeLabel(const CallGraphNode *Node,
267 const CallGraph *CG) {
268 if (CG->getRoot() == Node) {
271 if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl()))
272 return ND->getNameAsString();