1 //===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file was developed by the LLVM research group and is distributed under
6 // the University of Illinois Open Source License. See LICENSE.TXT for details.
8 //===----------------------------------------------------------------------===//
10 // This interface is used to build and manipulate a call graph, which is a very
11 // useful tool for interprocedural optimization.
13 // Every function in a module is represented as a node in the call graph. The
14 // callgraph node keeps track of which functions the are called by the function
15 // corresponding to the node.
17 // A call graph may contain nodes where the function that they correspond to is
18 // null. These 'external' nodes are used to represent control flow that is not
19 // represented (or analyzable) in the module. In particular, this analysis
20 // builds one external node such that:
21 // 1. All functions in the module without internal linkage will have edges
22 // from this external node, indicating that they could be called by
23 // functions outside of the module.
24 // 2. All functions whose address is used for something more than a direct
25 // call, for example being stored into a memory location will also have an
26 // edge from this external node. Since they may be called by an unknown
27 // caller later, they must be tracked as such.
29 // There is a second external node added for calls that leave this module.
30 // Functions have a call edge to the external node iff:
31 // 1. The function is external, reflecting the fact that they could call
32 // anything without internal linkage or that has its address taken.
33 // 2. The function contains an indirect function call.
35 // As an extension in the future, there may be multiple nodes with a null
36 // function. These will be used when we can prove (through pointer analysis)
37 // that an indirect call site can call only a specific set of functions.
39 // Because of these properties, the CallGraph captures a conservative superset
40 // of all of the caller-callee relationships, which is useful for
43 // The CallGraph class also attempts to figure out what the root of the
44 // CallGraph is, which it currently does by looking for a function named 'main'.
45 // If no function named 'main' is found, the external node is used as the entry
46 // node, reflecting the fact that any function without internal linkage could
47 // be called into (which is common for libraries).
49 //===----------------------------------------------------------------------===//
51 #ifndef LLVM_ANALYSIS_CALLGRAPH_H
52 #define LLVM_ANALYSIS_CALLGRAPH_H
54 #include "llvm/ADT/GraphTraits.h"
55 #include "llvm/ADT/STLExtras.h"
56 #include "llvm/Pass.h"
64 //===----------------------------------------------------------------------===//
65 // CallGraph class definition
69 Module *Mod; // The module this call graph represents
71 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
72 FunctionMapTy FunctionMap; // Map from a function to its node
75 //===---------------------------------------------------------------------
78 typedef FunctionMapTy::iterator iterator;
79 typedef FunctionMapTy::const_iterator const_iterator;
81 /// getModule - Return the module the call graph corresponds to.
83 Module &getModule() const { return *Mod; }
85 inline iterator begin() { return FunctionMap.begin(); }
86 inline iterator end() { return FunctionMap.end(); }
87 inline const_iterator begin() const { return FunctionMap.begin(); }
88 inline const_iterator end() const { return FunctionMap.end(); }
90 // Subscripting operators, return the call graph node for the provided
92 inline const CallGraphNode *operator[](const Function *F) const {
93 const_iterator I = FunctionMap.find(F);
94 assert(I != FunctionMap.end() && "Function not in callgraph!");
97 inline CallGraphNode *operator[](const Function *F) {
98 const_iterator I = FunctionMap.find(F);
99 assert(I != FunctionMap.end() && "Function not in callgraph!");
103 //Returns the CallGraphNode which is used to represent undetermined calls
104 // into the callgraph. Override this if you want behavioural inheritance.
105 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
107 //Return the root/main method in the module, or some other root node, such
108 // as the externalcallingnode. Overload these if you behavioural
110 virtual CallGraphNode* getRoot() { return 0; }
111 virtual const CallGraphNode* getRoot() const { return 0; }
113 //===---------------------------------------------------------------------
114 // Functions to keep a call graph up to date with a function that has been
118 /// removeFunctionFromModule - Unlink the function from this module, returning
119 /// it. Because this removes the function from the module, the call graph
120 /// node is destroyed. This is only valid if the function does not call any
121 /// other functions (ie, there are no edges in it's CGN). The easiest way to
122 /// do this is to dropAllReferences before calling this.
124 Function *removeFunctionFromModule(CallGraphNode *CGN);
125 Function *removeFunctionFromModule(Function *F) {
126 return removeFunctionFromModule((*this)[F]);
129 /// changeFunction - This method changes the function associated with this
130 /// CallGraphNode, for use by transformations that need to change the
131 /// prototype of a Function (thus they must create a new Function and move the
133 void changeFunction(Function *OldF, Function *NewF);
135 /// getOrInsertFunction - This method is identical to calling operator[], but
136 /// it will insert a new CallGraphNode for the specified function if one does
137 /// not already exist.
138 CallGraphNode *getOrInsertFunction(const Function *F);
140 //===---------------------------------------------------------------------
141 // Pass infrastructure interface glue code...
147 virtual ~CallGraph() { destroy(); }
149 /// initialize - Call this method before calling other methods,
150 /// re/initializes the state of the CallGraph.
152 void initialize(Module &M);
154 virtual void print(std::ostream &o, const Module *M) const;
157 // stub - dummy function, just ignore it
161 // destroy - Release memory for the call graph
162 virtual void destroy();
165 //===----------------------------------------------------------------------===//
166 // CallGraphNode class definition
168 class CallGraphNode {
170 std::vector<CallGraphNode*> CalledFunctions;
172 CallGraphNode(const CallGraphNode &); // Do not implement
174 //===---------------------------------------------------------------------
175 // Accessor methods...
178 typedef std::vector<CallGraphNode*>::iterator iterator;
179 typedef std::vector<CallGraphNode*>::const_iterator const_iterator;
181 // getFunction - Return the function that this call graph node represents...
182 Function *getFunction() const { return F; }
184 inline iterator begin() { return CalledFunctions.begin(); }
185 inline iterator end() { return CalledFunctions.end(); }
186 inline const_iterator begin() const { return CalledFunctions.begin(); }
187 inline const_iterator end() const { return CalledFunctions.end(); }
188 inline unsigned size() const { return CalledFunctions.size(); }
190 // Subscripting operator - Return the i'th called function...
192 CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];}
194 /// dump - Print out this call graph node.
197 void print(std::ostream &OS) const;
199 //===---------------------------------------------------------------------
200 // Methods to keep a call graph up to date with a function that has been
204 /// removeAllCalledFunctions - As the name implies, this removes all edges
205 /// from this CallGraphNode to any functions it calls.
206 void removeAllCalledFunctions() {
207 CalledFunctions.clear();
210 /// addCalledFunction add a function to the list of functions called by this
212 void addCalledFunction(CallGraphNode *M) {
213 CalledFunctions.push_back(M);
216 /// removeCallEdgeTo - This method removes a *single* edge to the specified
217 /// callee function. Note that this method takes linear time, so it should be
219 void removeCallEdgeTo(CallGraphNode *Callee);
221 /// removeAnyCallEdgeTo - This method removes any call edges from this node to
222 /// the specified callee function. This takes more time to execute than
223 /// removeCallEdgeTo, so it should not be used unless necessary.
224 void removeAnyCallEdgeTo(CallGraphNode *Callee);
226 friend class CallGraph;
228 // CallGraphNode ctor - Create a node for the specified function...
229 inline CallGraphNode(Function *f) : F(f) {}
232 //===----------------------------------------------------------------------===//
233 // GraphTraits specializations for call graphs so that they can be treated as
234 // graphs by the generic graph algorithms...
237 // Provide graph traits for tranversing call graphs using standard graph
239 template <> struct GraphTraits<CallGraphNode*> {
240 typedef CallGraphNode NodeType;
241 typedef NodeType::iterator ChildIteratorType;
243 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
244 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
245 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
248 template <> struct GraphTraits<const CallGraphNode*> {
249 typedef const CallGraphNode NodeType;
250 typedef NodeType::const_iterator ChildIteratorType;
252 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
253 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
254 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
257 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
258 static NodeType *getEntryNode(CallGraph *CGN) {
259 return CGN->getExternalCallingNode(); // Start at the external node!
261 typedef std::pair<const Function*, CallGraphNode*> PairTy;
262 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
264 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
265 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
266 static nodes_iterator nodes_begin(CallGraph *CG) {
267 return map_iterator(CG->begin(), DerefFun(CGdereference));
269 static nodes_iterator nodes_end (CallGraph *CG) {
270 return map_iterator(CG->end(), DerefFun(CGdereference));
273 static CallGraphNode &CGdereference (std::pair<const Function*,
279 template<> struct GraphTraits<const CallGraph*> :
280 public GraphTraits<const CallGraphNode*> {
281 static NodeType *getEntryNode(const CallGraph *CGN) {
282 return CGN->getExternalCallingNode();
284 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
285 typedef CallGraph::const_iterator nodes_iterator;
286 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
287 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
290 } // End llvm namespace
292 // Make sure that any clients of this file link in CallGraph.cpp
293 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)