CallGraph.cpp revision a5d531f67de0cfeb56b843da15146f3b4cd75bd9 
1//== CallGraph.cpp - AST-based Call graph  ----------------------*- C++ -*--==//
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//  This file defines the AST-based CallGraph.
11//
12//===----------------------------------------------------------------------===//
13#include "clang/Analysis/CallGraph.h"
14
15#include "clang/AST/ASTContext.h"
16#include "clang/AST/Decl.h"
17#include "clang/AST/StmtVisitor.h"
18
19#include "llvm/Support/GraphWriter.h"
20
21using namespace clang;
22
23/// Determine if a declaration should be included in the graph.
24static bool includeInGraph(const Decl *D) {
25  if (const FunctionDecl *FD = dyn_cast<FunctionDecl>(D)) {
26    // We skip function template definitions, as their semantics is
27    // only determined when they are instantiated.
28    if (!FD->isThisDeclarationADefinition() ||
29        FD->isDependentContext())
30      return false;
31
32    IdentifierInfo *II = FD->getIdentifier();
33    if (II && II->getName().startswith("__inline"))
34      return false;
35  }
36
37  if (const ObjCMethodDecl *ID = dyn_cast<ObjCMethodDecl>(D)) {
38    if (!ID->isThisDeclarationADefinition())
39      return false;
40  }
41
42  return true;
43}
44
45namespace {
46/// A helper class, which walks the AST and locates all the call sites in the
47/// given function body.
48class CGBuilder : public StmtVisitor<CGBuilder> {
49  CallGraph *G;
50  const Decl *FD;
51  CallGraphNode *CallerNode;
52
53public:
54  CGBuilder(CallGraph *g, const Decl *D, CallGraphNode *N)
55    : G(g), FD(D), CallerNode(N) {}
56
57  void VisitStmt(Stmt *S) { VisitChildren(S); }
58
59  void VisitCallExpr(CallExpr *CE) {
60    // TODO: We need to handle ObjC method calls as well.
61    if (FunctionDecl *CalleeDecl = CE->getDirectCallee())
62      if (includeInGraph(CalleeDecl)) {
63        CallGraphNode *CalleeNode = G->getOrInsertFunction(CalleeDecl);
64        CallerNode->addCallee(CalleeNode, G);
65      }
66  }
67
68  void VisitChildren(Stmt *S) {
69    for (Stmt::child_range I = S->children(); I; ++I)
70      if (*I)
71        static_cast<CGBuilder*>(this)->Visit(*I);
72  }
73};
74} // end anonymous namespace
75
76CallGraph::CallGraph() {
77  Root = getOrInsertFunction(0);
78}
79
80CallGraph::~CallGraph() {
81  if (!FunctionMap.empty()) {
82    for (FunctionMapTy::iterator I = FunctionMap.begin(), E = FunctionMap.end();
83        I != E; ++I)
84      delete I->second;
85    FunctionMap.clear();
86  }
87}
88
89void CallGraph::addToCallGraph(Decl* D, bool IsGlobal) {
90  assert(D);
91  CallGraphNode *Node = getOrInsertFunction(D);
92
93  if (IsGlobal)
94    Root->addCallee(Node, this);
95
96  // Process all the calls by this function as well.
97  CGBuilder builder(this, D, Node);
98  builder.Visit(D->getBody());
99}
100
101void CallGraph::addToCallGraph(DeclContext *DC) {
102  for (DeclContext::decl_iterator I = DC->decls_begin(), E = DC->decls_end();
103       I != E; ++I) {
104    Decl *D = *I;
105    switch (D->getKind()) {
106    case Decl::CXXConstructor:
107    case Decl::CXXDestructor:
108    case Decl::CXXConversion:
109    case Decl::CXXMethod:
110    case Decl::Function: {
111      FunctionDecl *FD = cast<FunctionDecl>(D);
112      // We skip function template definitions, as their semantics is
113      // only determined when they are instantiated.
114      if (includeInGraph(FD))
115        // If this function has external linkage, anything could call it.
116        // Note, we are not precise here. For example, the function could have
117        // its address taken.
118        addToCallGraph(FD, FD->isGlobal());
119      break;
120    }
121
122    case Decl::ObjCCategoryImpl:
123    case Decl::ObjCImplementation: {
124      ObjCImplDecl *ID = cast<ObjCImplDecl>(D);
125      for (ObjCContainerDecl::method_iterator MI = ID->meth_begin(),
126          ME = ID->meth_end(); MI != ME; ++MI) {
127        if (includeInGraph(*MI))
128          addToCallGraph(*MI, true);
129      }
130      break;
131    }
132
133    default:
134      break;
135    }
136  }
137}
138
139CallGraphNode *CallGraph::getNode(const Decl *F) const {
140  return FunctionMap.find(F)->second;
141}
142
143CallGraphNode *CallGraph::getOrInsertFunction(Decl *F) {
144  CallGraphNode *&Node = FunctionMap[F];
145  if (Node)
146    return Node;
147
148  Node = new CallGraphNode(F);
149  // If not root, add to the parentless list.
150  if (F != 0)
151    ParentlessNodes.insert(Node);
152  return Node;
153}
154
155void CallGraph::print(raw_ostream &OS) const {
156  OS << " --- Call graph Dump --- \n";
157  for (const_iterator I = begin(), E = end(); I != E; ++I) {
158    OS << "  Function: ";
159    if (I->second == Root)
160      OS << "< root >";
161    else
162      I->second->print(OS);
163    OS << " calls: ";
164    for (CallGraphNode::iterator CI = I->second->begin(),
165        CE = I->second->end(); CI != CE; ++CI) {
166      assert(*CI != Root && "No one can call the root node.");
167      (*CI)->print(OS);
168      OS << " ";
169    }
170    OS << '\n';
171  }
172  OS.flush();
173}
174
175void CallGraph::dump() const {
176  print(llvm::errs());
177}
178
179void CallGraph::viewGraph() const {
180  llvm::ViewGraph(this, "CallGraph");
181}
182
183StringRef CallGraphNode::getName() const {
184  if (const FunctionDecl *D = dyn_cast_or_null<FunctionDecl>(FD))
185    if (const IdentifierInfo *II = D->getIdentifier())
186      return II->getName();
187    return "< >";
188}
189
190void CallGraphNode::print(raw_ostream &os) const {
191  os << getName();
192}
193
194void CallGraphNode::dump() const {
195  print(llvm::errs());
196}
197
198namespace llvm {
199
200template <>
201struct DOTGraphTraits<const CallGraph*> : public DefaultDOTGraphTraits {
202
203  DOTGraphTraits (bool isSimple=false) : DefaultDOTGraphTraits(isSimple) {}
204
205  static std::string getNodeLabel(const CallGraphNode *Node,
206                                  const CallGraph *CG) {
207    if (CG->getRoot() == Node) {
208      return "< root >";
209    }
210    return Node->getName();
211  }
212
213};
214}
215