clang  10.0.0svn
CallGraph.cpp
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1 //===- CallGraph.cpp - AST-based Call graph -------------------------------===//
2 //
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
6 //
7 //===----------------------------------------------------------------------===//
8 //
9 // This file defines the AST-based CallGraph.
10 //
11 //===----------------------------------------------------------------------===//
12 
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"
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"
31 #include <cassert>
32 #include <memory>
33 #include <string>
34 
35 using namespace clang;
36 
37 #define DEBUG_TYPE "CallGraph"
38 
39 STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges");
40 STATISTIC(NumBlockCallEdges, "Number of block call edges");
41 
42 namespace {
43 
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> {
47  CallGraph *G;
48  CallGraphNode *CallerNode;
49 
50 public:
51  CGBuilder(CallGraph *g, CallGraphNode *N) : G(g), CallerNode(N) {}
52 
53  void VisitStmt(Stmt *S) { VisitChildren(S); }
54 
55  Decl *getDeclFromCall(CallExpr *CE) {
56  if (FunctionDecl *CalleeDecl = CE->getDirectCallee())
57  return CalleeDecl;
58 
59  // Simple detection of a call through a block.
60  Expr *CEE = CE->getCallee()->IgnoreParenImpCasts();
61  if (BlockExpr *Block = dyn_cast<BlockExpr>(CEE)) {
62  NumBlockCallEdges++;
63  return Block->getBlockDecl();
64  }
65 
66  return nullptr;
67  }
68 
69  void addCalledDecl(Decl *D) {
70  if (G->includeInGraph(D)) {
71  CallGraphNode *CalleeNode = G->getOrInsertNode(D);
72  CallerNode->addCallee(CalleeNode);
73  }
74  }
75 
76  void VisitCallExpr(CallExpr *CE) {
77  if (Decl *D = getDeclFromCall(CE))
78  addCalledDecl(D);
79  VisitChildren(CE);
80  }
81 
82  void VisitLambdaExpr(LambdaExpr *LE) {
84  for (FunctionDecl *FD : FTD->specializations())
85  G->VisitFunctionDecl(FD);
86  else if (CXXMethodDecl *MD = LE->getCallOperator())
87  G->VisitFunctionDecl(MD);
88  }
89 
90  void VisitCXXNewExpr(CXXNewExpr *E) {
91  if (FunctionDecl *FD = E->getOperatorNew())
92  addCalledDecl(FD);
93  VisitChildren(E);
94  }
95 
96  void VisitCXXConstructExpr(CXXConstructExpr *E) {
98  if (FunctionDecl *Def = Ctor->getDefinition())
99  addCalledDecl(Def);
100  VisitChildren(E);
101  }
102 
103  // Include the evaluation of the default argument.
104  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
105  Visit(E->getExpr());
106  }
107 
108  // Include the evaluation of the default initializers in a class.
109  void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
110  Visit(E->getExpr());
111  }
112 
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();
117 
118  // Find the callee definition within the same translation unit.
119  Decl *D = nullptr;
120  if (ME->isInstanceMessage())
121  D = IDecl->lookupPrivateMethod(Sel);
122  else
123  D = IDecl->lookupPrivateClassMethod(Sel);
124  if (D) {
125  addCalledDecl(D);
126  NumObjCCallEdges++;
127  }
128  }
129  }
130 
131  void VisitChildren(Stmt *S) {
132  for (Stmt *SubStmt : S->children())
133  if (SubStmt)
134  this->Visit(SubStmt);
135  }
136 };
137 
138 } // namespace
139 
141  if (BlockDecl *BD = dyn_cast<BlockDecl>(D))
142  addNodeForDecl(BD, true);
143 
144  for (auto *I : D->decls())
145  if (auto *DC = dyn_cast<DeclContext>(I))
146  addNodesForBlocks(DC);
147 }
148 
150  Root = getOrInsertNode(nullptr);
151 }
152 
153 CallGraph::~CallGraph() = default;
154 
156  assert(D);
157  if (!D->hasBody())
158  return false;
159 
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())
164  return false;
165 
166  IdentifierInfo *II = FD->getIdentifier();
167  if (II && II->getName().startswith("__inline"))
168  return false;
169  }
170 
171  return true;
172 }
173 
174 void CallGraph::addNodeForDecl(Decl* D, bool IsGlobal) {
175  assert(D);
176 
177  // Allocate a new node, mark it as root, and process its calls.
178  CallGraphNode *Node = getOrInsertNode(D);
179 
180  // Process all the calls by this function as well.
181  CGBuilder builder(this, Node);
182  if (Stmt *Body = D->getBody())
183  builder.Visit(Body);
184 
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());
189  }
190  }
191 }
192 
194  FunctionMapTy::const_iterator I = FunctionMap.find(F);
195  if (I == FunctionMap.end()) return nullptr;
196  return I->second.get();
197 }
198 
200  if (F && !isa<ObjCMethodDecl>(F))
201  F = F->getCanonicalDecl();
202 
203  std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];
204  if (Node)
205  return Node.get();
206 
207  Node = std::make_unique<CallGraphNode>(F);
208  // Make Root node a parent of all functions to make sure all are reachable.
209  if (F)
210  Root->addCallee(Node.get());
211  return Node.get();
212 }
213 
214 void CallGraph::print(raw_ostream &OS) const {
215  OS << " --- Call graph Dump --- \n";
216 
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;
223 
224  OS << " Function: ";
225  if (N == Root)
226  OS << "< root >";
227  else
228  N->print(OS);
229 
230  OS << " calls: ";
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.");
234  (*CI)->print(OS);
235  OS << " ";
236  }
237  OS << '\n';
238  }
239  OS.flush();
240 }
241 
242 LLVM_DUMP_METHOD void CallGraph::dump() const {
243  print(llvm::errs());
244 }
245 
246 void CallGraph::viewGraph() const {
247  llvm::ViewGraph(this, "CallGraph");
248 }
249 
250 void CallGraphNode::print(raw_ostream &os) const {
251  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(FD))
252  return ND->printQualifiedName(os);
253  os << "< >";
254 }
255 
256 LLVM_DUMP_METHOD void CallGraphNode::dump() const {
257  print(llvm::errs());
258 }
259 
260 namespace llvm {
261 
262 template <>
264  DOTGraphTraits (bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
265 
266  static std::string getNodeLabel(const CallGraphNode *Node,
267  const CallGraph *CG) {
268  if (CG->getRoot() == Node) {
269  return "< root >";
270  }
271  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl()))
272  return ND->getNameAsString();
273  else
274  return "< >";
275  }
276 };
277 
278 } // namespace llvm
The AST-based call graph.
Definition: CallGraph.h:41
FunctionDecl * getDefinition()
Get the definition for this declaration.
Definition: Decl.h:2005
Represents a function declaration or definition.
Definition: Decl.h:1784
Smart pointer class that efficiently represents Objective-C method names.
void dump() const
Definition: CallGraph.cpp:242
Selector getSelector() const
Definition: ExprObjC.cpp:337
virtual Stmt * getBody() const
getBody - If this Decl represents a declaration for a body of code, such as a function or method defi...
Definition: DeclBase.h:986
Specialize PointerLikeTypeTraits to allow LazyGenerationalUpdatePtr to be placed into a PointerUnion...
Definition: Dominators.h:30
Stmt - This represents one statement.
Definition: Stmt.h:66
ObjCInterfaceDecl * getReceiverInterface() const
Retrieve the Objective-C interface to which this message is being directed, if known.
Definition: ExprObjC.cpp:358
const T * get() const
Retrieve the stored node as type T.
Decl - This represents one declaration (or definition), e.g.
Definition: DeclBase.h:88
FunctionDecl * getOperatorNew() const
Definition: ExprCXX.h:2218
Represents a call to a C++ constructor.
Definition: ExprCXX.h:1422
void dump() const
Definition: CallGraph.cpp:256
DOTGraphTraits(bool isSimple=false)
Represents a C++ constructor within a class.
Definition: DeclCXX.h:2365
SmallVectorImpl< CallRecord >::const_iterator const_iterator
Definition: CallGraph.h:159
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:2028
CallGraphNode * getOrInsertNode(Decl *)
Lookup the node for the given declaration.
Definition: CallGraph.cpp:199
void addCallee(CallGraphNode *N)
Definition: CallGraph.h:170
void print(llvm::raw_ostream &OS, const Pointer &P, ASTContext &Ctx, QualType Ty)
Definition: InterpFrame.cpp:62
FunctionTemplateDecl * getDependentCallOperator() const
Retrieve the function template call operator associated with this lambda expression.
Definition: ExprCXX.cpp:1291
One of these records is kept for each identifier that is lexed.
Forward-declares and imports various common LLVM datatypes that clang wants to use unqualified...
child_range children()
Definition: Stmt.cpp:223
void addNodesForBlocks(DeclContext *D)
Definition: CallGraph.cpp:140
A C++ lambda expression, which produces a function object (of unspecified type) that can be invoked l...
Definition: ExprCXX.h:1818
Represents an ObjC class declaration.
Definition: DeclObjC.h:1171
A default argument (C++ [dcl.fct.default]).
Definition: ExprCXX.h:1202
virtual Decl * getCanonicalDecl()
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclBase.h:877
Decl * getDecl() const
Definition: CallGraph.h:174
const Expr * getExpr() const
Get the initialization expression that will be used.
Definition: ExprCXX.h:1307
CXXConstructorDecl * getConstructor() const
Get the constructor that this expression will (ultimately) call.
Definition: ExprCXX.h:1494
static std::string getNodeLabel(const CallGraphNode *Node, const CallGraph *CG)
Definition: CallGraph.cpp:266
STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges")
Represents a block literal declaration, which is like an unnamed FunctionDecl.
Definition: Decl.h:3951
This represents one expression.
Definition: Expr.h:108
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:5551
Expr * getCallee()
Definition: Expr.h:2638
FunctionDecl * getDirectCallee()
If the callee is a FunctionDecl, return it. Otherwise return null.
Definition: Expr.h:2656
Defines the clang::IdentifierInfo, clang::IdentifierTable, and clang::Selector interfaces.
An expression that sends a message to the given Objective-C object or class.
Definition: ExprObjC.h:950
void print(raw_ostream &os) const
Definition: CallGraph.cpp:214
CXXMethodDecl * getCallOperator() const
Retrieve the function call operator associated with this lambda expression.
Definition: ExprCXX.cpp:1286
virtual bool hasBody() const
Returns true if this Decl represents a declaration for a body of code, such as a function or method d...
Definition: DeclBase.h:992
bool VisitFunctionDecl(FunctionDecl *FD)
Part of recursive declaration visitation.
Definition: CallGraph.h:106
Represents a new-expression for memory allocation and constructor calls, e.g: "new CXXNewExpr(foo)"...
Definition: ExprCXX.h:2100
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:1905
static bool includeInGraph(const Decl *D)
Determine if a declaration should be included in the graph.
Definition: CallGraph.cpp:155
StmtVisitor - This class implements a simple visitor for Stmt subclasses.
Definition: StmtVisitor.h:182
void viewGraph() const
Definition: CallGraph.cpp:246
void print(raw_ostream &os) const
Definition: CallGraph.cpp:250
StringRef getName() const
Return the actual identifier string.
ast_type_traits::DynTypedNode Node
Dataflow Directional Tag Classes.
DeclContext - This is used only as base class of specific decl types that can act as declaration cont...
Definition: DeclBase.h:1271
CallGraphNode * getNode(const Decl *) const
Lookup the node for the given declaration.
Definition: CallGraph.cpp:193
CallGraphNode * getRoot() const
\ brief Get the virtual root of the graph, all the functions available externally are represented as ...
Definition: CallGraph.h:90
const Expr * getExpr() const
Definition: ExprCXX.h:1241
iterator begin()
Iterators through all the callees/children of the node.
Definition: CallGraph.h:162
Expr * IgnoreParenImpCasts() LLVM_READONLY
Skip past any parentheses and implicit casts which might surround this expression until reaching a fi...
Definition: Expr.cpp:2966
Represents a C++ base or member initializer.
Definition: DeclCXX.h:2137
A use of a default initializer in a constructor or in aggregate initialization.
Definition: ExprCXX.h:1279
bool LE(InterpState &S, CodePtr OpPC)
Definition: Interp.h:240
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2521
This represents a decl that may have a name.
Definition: Decl.h:248
bool isInstanceMessage() const
Determine whether this is an instance message to either a computed object or to super.
Definition: ExprObjC.h:1248
Declaration of a template function.
Definition: DeclTemplate.h:961