1 //===- CallGraph.h - AST-based Call graph -----------------------*- C++ -*-===//
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
7 //===----------------------------------------------------------------------===//
9 // This file declares the AST-based CallGraph.
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.
15 //===----------------------------------------------------------------------===//
17 #ifndef LLVM_CLANG_ANALYSIS_CALLGRAPH_H
18 #define LLVM_CLANG_ANALYSIS_CALLGRAPH_H
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"
36 /// The AST-based call graph.
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
41 class CallGraph : public RecursiveASTVisitor<CallGraph> {
42 friend class CallGraphNode;
45 llvm::DenseMap<const Decl *, std::unique_ptr<CallGraphNode>>;
47 /// FunctionMap owns all CallGraphNodes.
48 FunctionMapTy FunctionMap;
50 /// This is a virtual root node that has edges to all the functions.
57 /// Populate the call graph with the functions in the given
60 /// Recursively walks the declaration to find all the dependent Decls as well.
61 void addToCallGraph(Decl *D) {
65 /// Determine if a declaration should be included in the graph.
66 static bool includeInGraph(const Decl *D);
68 /// Lookup the node for the given declaration.
69 CallGraphNode *getNode(const Decl *) const;
71 /// Lookup the node for the given declaration. If none found, insert
72 /// one into the graph.
73 CallGraphNode *getOrInsertNode(Decl *);
75 using iterator = FunctionMapTy::iterator;
76 using const_iterator = FunctionMapTy::const_iterator;
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(); }
85 /// Get the number of nodes in the graph.
86 unsigned size() const { return FunctionMap.size(); }
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; }
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;
98 void print(raw_ostream &os) const;
100 void viewGraph() const;
102 void addNodesForBlocks(DeclContext *D);
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());
120 /// Part of recursive declaration visitation.
121 bool VisitObjCMethodDecl(ObjCMethodDecl *MD) {
122 if (includeInGraph(MD)) {
123 addNodesForBlocks(MD);
124 addNodeForDecl(MD, true);
129 // We are only collecting the declarations, so do not step into the bodies.
130 bool TraverseStmt(Stmt *S) { return true; }
132 bool shouldWalkTypesOfTypeLocs() const { return false; }
133 bool shouldVisitTemplateInstantiations() const { return true; }
136 /// Add the given declaration to the call graph.
137 void addNodeForDecl(Decl *D, bool IsGlobal);
139 /// Allocate a new node in the graph.
140 CallGraphNode *allocateNewNode(Decl *);
143 class CallGraphNode {
145 using CallRecord = CallGraphNode *;
148 /// The function/method declaration.
151 /// The list of functions called from this node.
152 SmallVector<CallRecord, 5> CalledFunctions;
155 CallGraphNode(Decl *D) : FD(D) {}
157 using iterator = SmallVectorImpl<CallRecord>::iterator;
158 using const_iterator = SmallVectorImpl<CallRecord>::const_iterator;
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(); }
166 bool empty() const { return CalledFunctions.empty(); }
167 unsigned size() const { return CalledFunctions.size(); }
169 void addCallee(CallGraphNode *N) {
170 CalledFunctions.push_back(N);
173 Decl *getDecl() const { return FD; }
175 void print(raw_ostream &os) const;
181 // Graph traits for iteration, viewing.
184 template <> struct GraphTraits<clang::CallGraphNode*> {
185 using NodeType = clang::CallGraphNode;
186 using NodeRef = clang::CallGraphNode *;
187 using ChildIteratorType = NodeType::iterator;
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(); }
194 template <> struct GraphTraits<const clang::CallGraphNode*> {
195 using NodeType = const clang::CallGraphNode;
196 using NodeRef = const clang::CallGraphNode *;
197 using ChildIteratorType = NodeType::const_iterator;
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(); }
204 template <> 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!
210 static clang::CallGraphNode *
211 CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
212 return P.second.get();
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)>;
219 static nodes_iterator nodes_begin(clang::CallGraph *CG) {
220 return nodes_iterator(CG->begin(), &CGGetValue);
223 static nodes_iterator nodes_end (clang::CallGraph *CG) {
224 return nodes_iterator(CG->end(), &CGGetValue);
227 static unsigned size(clang::CallGraph *CG) { return CG->size(); }
230 template <> struct GraphTraits<const clang::CallGraph*> :
231 public GraphTraits<const clang::CallGraphNode*> {
232 static NodeType *getEntryNode(const clang::CallGraph *CGN) {
233 return CGN->getRoot();
236 static clang::CallGraphNode *
237 CGGetValue(clang::CallGraph::const_iterator::value_type &P) {
238 return P.second.get();
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)>;
245 static nodes_iterator nodes_begin(const clang::CallGraph *CG) {
246 return nodes_iterator(CG->begin(), &CGGetValue);
249 static nodes_iterator nodes_end(const clang::CallGraph *CG) {
250 return nodes_iterator(CG->end(), &CGGetValue);
253 static unsigned size(const clang::CallGraph *CG) { return CG->size(); }
258 #endif // LLVM_CLANG_ANALYSIS_CALLGRAPH_H