1//===- CallGraph.h - AST-based Call graph -----------------------*- C++ -*-===//
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 declares the AST-based CallGraph.
10//
11// A call graph for functions whose definitions/bodies are available in the
12// current translation unit. The graph has a "virtual" root node that contains
13// edges to all externally available functions.
14//
15//===----------------------------------------------------------------------===//
16
17#ifndef LLVM_CLANG_ANALYSIS_CALLGRAPH_H
18#define LLVM_CLANG_ANALYSIS_CALLGRAPH_H
19
20#include "clang/AST/Decl.h"
21#include "clang/AST/RecursiveASTVisitor.h"
22#include "llvm/ADT/DenseMap.h"
23#include "llvm/ADT/GraphTraits.h"
24#include "llvm/ADT/STLExtras.h"
25#include "llvm/ADT/SetVector.h"
26#include "llvm/ADT/SmallVector.h"
27#include <memory>
28
29namespace clang {
30
31class CallGraphNode;
32class Decl;
33class DeclContext;
34class Stmt;
35
36/// The AST-based call graph.
37///
38/// The call graph extends itself with the given declarations by implementing
39/// the recursive AST visitor, which constructs the graph by visiting the given
40/// declarations.
41class CallGraph : public RecursiveASTVisitor<CallGraph> {
42 friend class CallGraphNode;
43
44 using FunctionMapTy =
45 llvm::DenseMap<const Decl *, std::unique_ptr<CallGraphNode>>;
46
47 /// FunctionMap owns all CallGraphNodes.
48 FunctionMapTy FunctionMap;
49
50 /// This is a virtual root node that has edges to all the functions.
51 CallGraphNode *Root;
52
53public:
54 CallGraph();
55 ~CallGraph();
56
57 /// Populate the call graph with the functions in the given
58 /// declaration.
59 ///
60 /// Recursively walks the declaration to find all the dependent Decls as well.
61 void addToCallGraph(Decl *D) {
62 TraverseDecl(D);
63 }
64
65 /// Determine if a declaration should be included in the graph.
66 static bool includeInGraph(const Decl *D);
67
68 /// Lookup the node for the given declaration.
69 CallGraphNode *getNode(const Decl *) const;
70
71 /// Lookup the node for the given declaration. If none found, insert
72 /// one into the graph.
73 CallGraphNode *getOrInsertNode(Decl *);
74
75 using iterator = FunctionMapTy::iterator;
76 using const_iterator = FunctionMapTy::const_iterator;
77
78 /// Iterators through all the elements in the graph. Note, this gives
79 /// non-deterministic order.
80 iterator begin() { return FunctionMap.begin(); }
81 iterator end() { return FunctionMap.end(); }
82 const_iterator begin() const { return FunctionMap.begin(); }
83 const_iterator end() const { return FunctionMap.end(); }
84
85 /// Get the number of nodes in the graph.
86 unsigned size() const { return FunctionMap.size(); }
87
88 /// \ brief Get the virtual root of the graph, all the functions available
89 /// externally are represented as callees of the node.
90 CallGraphNode *getRoot() const { return Root; }
91
92 /// Iterators through all the nodes of the graph that have no parent. These
93 /// are the unreachable nodes, which are either unused or are due to us
94 /// failing to add a call edge due to the analysis imprecision.
95 using nodes_iterator = llvm::SetVector<CallGraphNode *>::iterator;
96 using const_nodes_iterator = llvm::SetVector<CallGraphNode *>::const_iterator;
97
98 void print(raw_ostream &os) const;
99 void dump() const;
100 void viewGraph() const;
101
102 void addNodesForBlocks(DeclContext *D);
103
104 /// Part of recursive declaration visitation. We recursively visit all the
105 /// declarations to collect the root functions.
106 bool VisitFunctionDecl(FunctionDecl *FD) {
107 // We skip function template definitions, as their semantics is
108 // only determined when they are instantiated.
109 if (includeInGraph(FD) && FD->isThisDeclarationADefinition()) {
110 // Add all blocks declared inside this function to the graph.
111 addNodesForBlocks(FD);
112 // If this function has external linkage, anything could call it.
113 // Note, we are not precise here. For example, the function could have
114 // its address taken.
115 addNodeForDecl(FD, FD->isGlobal());
116 }
117 return true;
118 }
119
120 /// Part of recursive declaration visitation.
121 bool VisitObjCMethodDecl(ObjCMethodDecl *MD) {
122 if (includeInGraph(MD)) {
123 addNodesForBlocks(MD);
124 addNodeForDecl(MD, true);
125 }
126 return true;
127 }
128
129 // We are only collecting the declarations, so do not step into the bodies.
130 bool TraverseStmt(Stmt *S) { return true; }
131
132 bool shouldWalkTypesOfTypeLocs() const { return false; }
133 bool shouldVisitTemplateInstantiations() const { return true; }
134
135private:
136 /// Add the given declaration to the call graph.
137 void addNodeForDecl(Decl *D, bool IsGlobal);
138
139 /// Allocate a new node in the graph.
140 CallGraphNode *allocateNewNode(Decl *);
141};
142
143class CallGraphNode {
144public:
145 using CallRecord = CallGraphNode *;
146
147private:
148 /// The function/method declaration.
149 Decl *FD;
150
151 /// The list of functions called from this node.
152 SmallVector<CallRecord, 5> CalledFunctions;
153
154public:
155 CallGraphNode(Decl *D) : FD(D) {}
156
157 using iterator = SmallVectorImpl<CallRecord>::iterator;
158 using const_iterator = SmallVectorImpl<CallRecord>::const_iterator;
159
160 /// Iterators through all the callees/children of the node.
161 iterator begin() { return CalledFunctions.begin(); }
162 iterator end() { return CalledFunctions.end(); }
163 const_iterator begin() const { return CalledFunctions.begin(); }
164 const_iterator end() const { return CalledFunctions.end(); }
165
166 bool empty() const { return CalledFunctions.empty(); }
167 unsigned size() const { return CalledFunctions.size(); }
168
169 void addCallee(CallGraphNode *N) {
170 CalledFunctions.push_back(N);
171 }
172
173 Decl *getDecl() const { return FD; }
174
175 void print(raw_ostream &os) const;
176 void dump() const;
177};
178
179} // namespace clang
180
181// Graph traits for iteration, viewing.
182namespace llvm {
183
184template <> struct GraphTraits<clang::CallGraphNode*> {
185 using NodeType = clang::CallGraphNode;
186 using NodeRef = clang::CallGraphNode *;
187 using ChildIteratorType = NodeType::iterator;
188
189 static NodeType *getEntryNode(clang::CallGraphNode *CGN) { return CGN; }
190 static ChildIteratorType child_begin(NodeType *N) { return N->begin(); }
191 static ChildIteratorType child_end(NodeType *N) { return N->end(); }
192};
193
194template <> struct GraphTraits<const clang::CallGraphNode*> {
195 using NodeType = const clang::CallGraphNode;
196 using NodeRef = const clang::CallGraphNode *;
197 using ChildIteratorType = NodeType::const_iterator;
198
199 static NodeType *getEntryNode(const clang::CallGraphNode *CGN) { return CGN; }
200 static ChildIteratorType child_begin(NodeType *N) { return N->begin();}
201 static ChildIteratorType child_end(NodeType *N) { return N->end(); }
202};
203
204template <> struct GraphTraits<clang::CallGraph*>
205 : public GraphTraits<clang::CallGraphNode*> {
206 static NodeType *getEntryNode(clang::CallGraph *CGN) {
207 return CGN->getRoot(); // Start at the external node!
208 }
209
210 static clang::CallGraphNode *
211 CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
212 return P.second.get();
213 }
214
215 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
216 using nodes_iterator =
217 mapped_iterator<clang::CallGraph::iterator, decltype(&CGGetValue)>;
218
219 static nodes_iterator nodes_begin(clang::CallGraph *CG) {
220 return nodes_iterator(CG->begin(), &CGGetValue);
221 }
222
223 static nodes_iterator nodes_end (clang::CallGraph *CG) {
224 return nodes_iterator(CG->end(), &CGGetValue);
225 }
226
227 static unsigned size(clang::CallGraph *CG) { return CG->size(); }
228};
229
230template <> struct GraphTraits<const clang::CallGraph*> :
231 public GraphTraits<const clang::CallGraphNode*> {
232 static NodeType *getEntryNode(const clang::CallGraph *CGN) {
233 return CGN->getRoot();
234 }
235
236 static clang::CallGraphNode *
237 CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
238 return P.second.get();
239 }
240
241 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
242 using nodes_iterator =
243 mapped_iterator<clang::CallGraph::const_iterator, decltype(&CGGetValue)>;
244
245 static nodes_iterator nodes_begin(const clang::CallGraph *CG) {
246 return nodes_iterator(CG->begin(), &CGGetValue);
247 }
248
249 static nodes_iterator nodes_end(const clang::CallGraph *CG) {
250 return nodes_iterator(CG->end(), &CGGetValue);
251 }
252
253 static unsigned size(const clang::CallGraph *CG) { return CG->size(); }
254};
255
256} // namespace llvm
257
258#endif // LLVM_CLANG_ANALYSIS_CALLGRAPH_H
259