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) {
83  if (CXXMethodDecl *MD = LE->getCallOperator())
84  G->VisitFunctionDecl(MD);
85  }
86 
87  void VisitCXXNewExpr(CXXNewExpr *E) {
88  if (FunctionDecl *FD = E->getOperatorNew())
89  addCalledDecl(FD);
90  VisitChildren(E);
91  }
92 
93  void VisitCXXConstructExpr(CXXConstructExpr *E) {
95  if (FunctionDecl *Def = Ctor->getDefinition())
96  addCalledDecl(Def);
97  VisitChildren(E);
98  }
99 
100  // Include the evaluation of the default argument.
101  void VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
102  Visit(E->getExpr());
103  }
104 
105  // Include the evaluation of the default initializers in a class.
106  void VisitCXXDefaultInitExpr(CXXDefaultInitExpr *E) {
107  Visit(E->getExpr());
108  }
109 
110  // Adds may-call edges for the ObjC message sends.
111  void VisitObjCMessageExpr(ObjCMessageExpr *ME) {
112  if (ObjCInterfaceDecl *IDecl = ME->getReceiverInterface()) {
113  Selector Sel = ME->getSelector();
114 
115  // Find the callee definition within the same translation unit.
116  Decl *D = nullptr;
117  if (ME->isInstanceMessage())
118  D = IDecl->lookupPrivateMethod(Sel);
119  else
120  D = IDecl->lookupPrivateClassMethod(Sel);
121  if (D) {
122  addCalledDecl(D);
123  NumObjCCallEdges++;
124  }
125  }
126  }
127 
128  void VisitChildren(Stmt *S) {
129  for (Stmt *SubStmt : S->children())
130  if (SubStmt)
131  this->Visit(SubStmt);
132  }
133 };
134 
135 } // namespace
136 
138  if (BlockDecl *BD = dyn_cast<BlockDecl>(D))
139  addNodeForDecl(BD, true);
140 
141  for (auto *I : D->decls())
142  if (auto *DC = dyn_cast<DeclContext>(I))
143  addNodesForBlocks(DC);
144 }
145 
147  Root = getOrInsertNode(nullptr);
148 }
149 
150 CallGraph::~CallGraph() = default;
151 
153  assert(D);
154  if (!D->hasBody())
155  return false;
156 
157  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
158  // We skip function template definitions, as their semantics is
159  // only determined when they are instantiated.
160  if (FD->isDependentContext())
161  return false;
162 
163  IdentifierInfo *II = FD->getIdentifier();
164  if (II && II->getName().startswith("__inline"))
165  return false;
166  }
167 
168  return true;
169 }
170 
171 void CallGraph::addNodeForDecl(Decl* D, bool IsGlobal) {
172  assert(D);
173 
174  // Allocate a new node, mark it as root, and process its calls.
175  CallGraphNode *Node = getOrInsertNode(D);
176 
177  // Process all the calls by this function as well.
178  CGBuilder builder(this, Node);
179  if (Stmt *Body = D->getBody())
180  builder.Visit(Body);
181 
182  // Include C++ constructor member initializers.
183  if (auto constructor = dyn_cast<CXXConstructorDecl>(D)) {
184  for (CXXCtorInitializer *init : constructor->inits()) {
185  builder.Visit(init->getInit());
186  }
187  }
188 }
189 
191  FunctionMapTy::const_iterator I = FunctionMap.find(F);
192  if (I == FunctionMap.end()) return nullptr;
193  return I->second.get();
194 }
195 
197  if (F && !isa<ObjCMethodDecl>(F))
198  F = F->getCanonicalDecl();
199 
200  std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];
201  if (Node)
202  return Node.get();
203 
204  Node = std::make_unique<CallGraphNode>(F);
205  // Make Root node a parent of all functions to make sure all are reachable.
206  if (F)
207  Root->addCallee(Node.get());
208  return Node.get();
209 }
210 
211 void CallGraph::print(raw_ostream &OS) const {
212  OS << " --- Call graph Dump --- \n";
213 
214  // We are going to print the graph in reverse post order, partially, to make
215  // sure the output is deterministic.
216  llvm::ReversePostOrderTraversal<const CallGraph *> RPOT(this);
217  for (llvm::ReversePostOrderTraversal<const CallGraph *>::rpo_iterator
218  I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
219  const CallGraphNode *N = *I;
220 
221  OS << " Function: ";
222  if (N == Root)
223  OS << "< root >";
224  else
225  N->print(OS);
226 
227  OS << " calls: ";
228  for (CallGraphNode::const_iterator CI = N->begin(),
229  CE = N->end(); CI != CE; ++CI) {
230  assert(*CI != Root && "No one can call the root node.");
231  (*CI)->print(OS);
232  OS << " ";
233  }
234  OS << '\n';
235  }
236  OS.flush();
237 }
238 
239 LLVM_DUMP_METHOD void CallGraph::dump() const {
240  print(llvm::errs());
241 }
242 
243 void CallGraph::viewGraph() const {
244  llvm::ViewGraph(this, "CallGraph");
245 }
246 
247 void CallGraphNode::print(raw_ostream &os) const {
248  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(FD))
249  return ND->printQualifiedName(os);
250  os << "< >";
251 }
252 
253 LLVM_DUMP_METHOD void CallGraphNode::dump() const {
254  print(llvm::errs());
255 }
256 
257 namespace llvm {
258 
259 template <>
261  DOTGraphTraits (bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
262 
263  static std::string getNodeLabel(const CallGraphNode *Node,
264  const CallGraph *CG) {
265  if (CG->getRoot() == Node) {
266  return "< root >";
267  }
268  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl()))
269  return ND->getNameAsString();
270  else
271  return "< >";
272  }
273 };
274 
275 } // namespace llvm
The AST-based call graph.
Definition: CallGraph.h:41
FunctionDecl * getDefinition()
Get the definition for this declaration.
Definition: Decl.h:1969
Represents a function declaration or definition.
Definition: Decl.h:1748
Smart pointer class that efficiently represents Objective-C method names.
void dump() const
Definition: CallGraph.cpp:239
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:2124
Represents a call to a C++ constructor.
Definition: ExprCXX.h:1331
void dump() const
Definition: CallGraph.cpp:253
DOTGraphTraits(bool isSimple=false)
Represents a C++ constructor within a class.
Definition: DeclCXX.h:2574
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:2021
CallGraphNode * getOrInsertNode(Decl *)
Lookup the node for the given declaration.
Definition: CallGraph.cpp:196
void addCallee(CallGraphNode *N)
Definition: CallGraph.h:170
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:212
void addNodesForBlocks(DeclContext *D)
Definition: CallGraph.cpp:137
A C++ lambda expression, which produces a function object (of unspecified type) that can be invoked l...
Definition: ExprCXX.h:1727
Represents an ObjC class declaration.
Definition: DeclObjC.h:1171
A default argument (C++ [dcl.fct.default]).
Definition: ExprCXX.h:1111
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:1216
CXXConstructorDecl * getConstructor() const
Get the constructor that this expression will (ultimately) call.
Definition: ExprCXX.h:1403
static std::string getNodeLabel(const CallGraphNode *Node, const CallGraph *CG)
Definition: CallGraph.cpp:263
STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges")
Represents a block literal declaration, which is like an unnamed FunctionDecl.
Definition: Decl.h:3891
This represents one expression.
Definition: Expr.h:108
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:5540
Expr * getCallee()
Definition: Expr.h:2633
FunctionDecl * getDirectCallee()
If the callee is a FunctionDecl, return it. Otherwise return null.
Definition: Expr.h:2651
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:211
CXXMethodDecl * getCallOperator() const
Retrieve the function call operator associated with this lambda expression.
Definition: ExprCXX.cpp:1210
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:2005
Represents a static or instance method of a struct/union/class.
Definition: DeclCXX.h:2114
static bool includeInGraph(const Decl *D)
Determine if a declaration should be included in the graph.
Definition: CallGraph.cpp:152
StmtVisitor - This class implements a simple visitor for Stmt subclasses.
Definition: StmtVisitor.h:182
void viewGraph() const
Definition: CallGraph.cpp:243
void print(raw_ostream &os) const
Definition: CallGraph.cpp:247
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:190
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:1150
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:2960
Represents a C++ base or member initializer.
Definition: DeclCXX.h:2346
A use of a default initializer in a constructor or in aggregate initialization.
Definition: ExprCXX.h:1188
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2516
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