clang  9.0.0svn
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  // Adds may-call edges for the ObjC message sends.
83  void VisitObjCMessageExpr(ObjCMessageExpr *ME) {
84  if (ObjCInterfaceDecl *IDecl = ME->getReceiverInterface()) {
85  Selector Sel = ME->getSelector();
86 
87  // Find the callee definition within the same translation unit.
88  Decl *D = nullptr;
89  if (ME->isInstanceMessage())
90  D = IDecl->lookupPrivateMethod(Sel);
91  else
92  D = IDecl->lookupPrivateClassMethod(Sel);
93  if (D) {
94  addCalledDecl(D);
95  NumObjCCallEdges++;
96  }
97  }
98  }
99 
100  void VisitChildren(Stmt *S) {
101  for (Stmt *SubStmt : S->children())
102  if (SubStmt)
103  this->Visit(SubStmt);
104  }
105 };
106 
107 } // namespace
108 
110  if (BlockDecl *BD = dyn_cast<BlockDecl>(D))
111  addNodeForDecl(BD, true);
112 
113  for (auto *I : D->decls())
114  if (auto *DC = dyn_cast<DeclContext>(I))
115  addNodesForBlocks(DC);
116 }
117 
119  Root = getOrInsertNode(nullptr);
120 }
121 
122 CallGraph::~CallGraph() = default;
123 
125  assert(D);
126  if (!D->hasBody())
127  return false;
128 
129  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
130  // We skip function template definitions, as their semantics is
131  // only determined when they are instantiated.
132  if (FD->isDependentContext())
133  return false;
134 
135  IdentifierInfo *II = FD->getIdentifier();
136  if (II && II->getName().startswith("__inline"))
137  return false;
138  }
139 
140  return true;
141 }
142 
143 void CallGraph::addNodeForDecl(Decl* D, bool IsGlobal) {
144  assert(D);
145 
146  // Allocate a new node, mark it as root, and process it's calls.
147  CallGraphNode *Node = getOrInsertNode(D);
148 
149  // Process all the calls by this function as well.
150  CGBuilder builder(this, Node);
151  if (Stmt *Body = D->getBody())
152  builder.Visit(Body);
153 }
154 
156  FunctionMapTy::const_iterator I = FunctionMap.find(F);
157  if (I == FunctionMap.end()) return nullptr;
158  return I->second.get();
159 }
160 
162  if (F && !isa<ObjCMethodDecl>(F))
163  F = F->getCanonicalDecl();
164 
165  std::unique_ptr<CallGraphNode> &Node = FunctionMap[F];
166  if (Node)
167  return Node.get();
168 
169  Node = llvm::make_unique<CallGraphNode>(F);
170  // Make Root node a parent of all functions to make sure all are reachable.
171  if (F)
172  Root->addCallee(Node.get());
173  return Node.get();
174 }
175 
176 void CallGraph::print(raw_ostream &OS) const {
177  OS << " --- Call graph Dump --- \n";
178 
179  // We are going to print the graph in reverse post order, partially, to make
180  // sure the output is deterministic.
181  llvm::ReversePostOrderTraversal<const CallGraph *> RPOT(this);
182  for (llvm::ReversePostOrderTraversal<const CallGraph *>::rpo_iterator
183  I = RPOT.begin(), E = RPOT.end(); I != E; ++I) {
184  const CallGraphNode *N = *I;
185 
186  OS << " Function: ";
187  if (N == Root)
188  OS << "< root >";
189  else
190  N->print(OS);
191 
192  OS << " calls: ";
193  for (CallGraphNode::const_iterator CI = N->begin(),
194  CE = N->end(); CI != CE; ++CI) {
195  assert(*CI != Root && "No one can call the root node.");
196  (*CI)->print(OS);
197  OS << " ";
198  }
199  OS << '\n';
200  }
201  OS.flush();
202 }
203 
204 LLVM_DUMP_METHOD void CallGraph::dump() const {
205  print(llvm::errs());
206 }
207 
208 void CallGraph::viewGraph() const {
209  llvm::ViewGraph(this, "CallGraph");
210 }
211 
212 void CallGraphNode::print(raw_ostream &os) const {
213  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(FD))
214  return ND->printQualifiedName(os);
215  os << "< >";
216 }
217 
218 LLVM_DUMP_METHOD void CallGraphNode::dump() const {
219  print(llvm::errs());
220 }
221 
222 namespace llvm {
223 
224 template <>
226  DOTGraphTraits (bool isSimple = false) : DefaultDOTGraphTraits(isSimple) {}
227 
228  static std::string getNodeLabel(const CallGraphNode *Node,
229  const CallGraph *CG) {
230  if (CG->getRoot() == Node) {
231  return "< root >";
232  }
233  if (const NamedDecl *ND = dyn_cast_or_null<NamedDecl>(Node->getDecl()))
234  return ND->getNameAsString();
235  else
236  return "< >";
237  }
238 };
239 
240 } // namespace llvm
The AST-based call graph.
Definition: CallGraph.h:41
Represents a function declaration or definition.
Definition: Decl.h:1743
Smart pointer class that efficiently represents Objective-C method names.
void dump() const
Definition: CallGraph.cpp:204
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:979
DominatorTree GraphTraits specialization so the DominatorTree can be iterable by generic graph iterat...
Definition: Dominators.h:29
Stmt - This represents one statement.
Definition: Stmt.h:65
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
void dump() const
Definition: CallGraph.cpp:218
SmallVectorImpl< CallRecord >::const_iterator const_iterator
Definition: CallGraph.h:158
decl_range decls() const
decls_begin/decls_end - Iterate over the declarations stored in this context.
Definition: DeclBase.h:2012
CallGraphNode * getOrInsertNode(Decl *)
Lookup the node for the given declaration.
Definition: CallGraph.cpp:161
void addCallee(CallGraphNode *N)
Definition: CallGraph.h:169
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:109
Represents an ObjC class declaration.
Definition: DeclObjC.h:1171
virtual Decl * getCanonicalDecl()
Retrieves the "canonical" declaration of the given declaration.
Definition: DeclBase.h:870
Decl * getDecl() const
Definition: CallGraph.h:173
static std::string getNodeLabel(const CallGraphNode *Node, const CallGraph *CG)
Definition: CallGraph.cpp:228
STATISTIC(NumObjCCallEdges, "Number of Objective-C method call edges")
Represents a block literal declaration, which is like an unnamed FunctionDecl.
Definition: Decl.h:3863
This represents one expression.
Definition: Expr.h:108
BlockExpr - Adaptor class for mixing a BlockDecl with expressions.
Definition: Expr.h:5461
Expr * getCallee()
Definition: Expr.h:2552
DOTGraphTraits(bool isSimple=false)
FunctionDecl * getDirectCallee()
If the callee is a FunctionDecl, return it. Otherwise return null.
Definition: Expr.h:2570
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:176
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:985
static bool includeInGraph(const Decl *D)
Determine if a declaration should be included in the graph.
Definition: CallGraph.cpp:124
StmtVisitor - This class implements a simple visitor for Stmt subclasses.
Definition: StmtVisitor.h:182
void viewGraph() const
Definition: CallGraph.cpp:208
void print(raw_ostream &os) const
Definition: CallGraph.cpp:212
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:1264
CallGraphNode * getNode(const Decl *) const
Lookup the node for the given declaration.
Definition: CallGraph.cpp:155
CallGraphNode * getRoot() const
\ brief Get the virtual root of the graph, all the functions available externally are represented as ...
Definition: CallGraph.h:90
iterator begin()
Iterators through all the callees/children of the node.
Definition: CallGraph.h:161
Expr * IgnoreParenImpCasts() LLVM_READONLY
Skip past any parentheses and implicit casts which might surround this expression until reaching a fi...
Definition: Expr.cpp:2809
CallExpr - Represents a function call (C99 6.5.2.2, C++ [expr.call]).
Definition: Expr.h:2434
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