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"
57 #include "llvm/Support/CallSite.h"
65 //===----------------------------------------------------------------------===//
66 // CallGraph class definition
70 Module *Mod; // The module this call graph represents
72 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
73 FunctionMapTy FunctionMap; // Map from a function to its node
76 //===---------------------------------------------------------------------
79 typedef FunctionMapTy::iterator iterator;
80 typedef FunctionMapTy::const_iterator const_iterator;
82 /// getModule - Return the module the call graph corresponds to.
84 Module &getModule() const { return *Mod; }
86 inline iterator begin() { return FunctionMap.begin(); }
87 inline iterator end() { return FunctionMap.end(); }
88 inline const_iterator begin() const { return FunctionMap.begin(); }
89 inline const_iterator end() const { return FunctionMap.end(); }
91 // Subscripting operators, return the call graph node for the provided
93 inline const CallGraphNode *operator[](const Function *F) const {
94 const_iterator I = FunctionMap.find(F);
95 assert(I != FunctionMap.end() && "Function not in callgraph!");
98 inline CallGraphNode *operator[](const Function *F) {
99 const_iterator I = FunctionMap.find(F);
100 assert(I != FunctionMap.end() && "Function not in callgraph!");
104 //Returns the CallGraphNode which is used to represent undetermined calls
105 // into the callgraph. Override this if you want behavioural inheritance.
106 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
108 //Return the root/main method in the module, or some other root node, such
109 // as the externalcallingnode. Overload these if you behavioural
111 virtual CallGraphNode* getRoot() { return 0; }
112 virtual const CallGraphNode* getRoot() const { return 0; }
114 //===---------------------------------------------------------------------
115 // Functions to keep a call graph up to date with a function that has been
119 /// removeFunctionFromModule - Unlink the function from this module, returning
120 /// it. Because this removes the function from the module, the call graph
121 /// node is destroyed. This is only valid if the function does not call any
122 /// other functions (ie, there are no edges in it's CGN). The easiest way to
123 /// do this is to dropAllReferences before calling this.
125 Function *removeFunctionFromModule(CallGraphNode *CGN);
126 Function *removeFunctionFromModule(Function *F) {
127 return removeFunctionFromModule((*this)[F]);
130 /// changeFunction - This method changes the function associated with this
131 /// CallGraphNode, for use by transformations that need to change the
132 /// prototype of a Function (thus they must create a new Function and move the
134 void changeFunction(Function *OldF, Function *NewF);
136 /// getOrInsertFunction - This method is identical to calling operator[], but
137 /// it will insert a new CallGraphNode for the specified function if one does
138 /// not already exist.
139 CallGraphNode *getOrInsertFunction(const Function *F);
141 //===---------------------------------------------------------------------
142 // Pass infrastructure interface glue code...
148 virtual ~CallGraph() { destroy(); }
150 /// initialize - Call this method before calling other methods,
151 /// re/initializes the state of the CallGraph.
153 void initialize(Module &M);
155 void print(llvm_ostream &o, const Module *M) const {
156 if (o.stream()) print(*o.stream(), M);
158 virtual void print(std::ostream &o, const Module *M) const;
161 // stub - dummy function, just ignore it
165 // destroy - Release memory for the call graph
166 virtual void destroy();
169 //===----------------------------------------------------------------------===//
170 // CallGraphNode class definition
172 class CallGraphNode {
174 typedef std::pair<CallSite,CallGraphNode*> CallRecord;
175 std::vector<CallRecord> CalledFunctions;
177 CallGraphNode(const CallGraphNode &); // Do not implement
179 //===---------------------------------------------------------------------
180 // Accessor methods...
183 typedef std::vector<CallRecord>::iterator iterator;
184 typedef std::vector<CallRecord>::const_iterator const_iterator;
186 // getFunction - Return the function that this call graph node represents...
187 Function *getFunction() const { return F; }
189 inline iterator begin() { return CalledFunctions.begin(); }
190 inline iterator end() { return CalledFunctions.end(); }
191 inline const_iterator begin() const { return CalledFunctions.begin(); }
192 inline const_iterator end() const { return CalledFunctions.end(); }
193 inline unsigned size() const { return CalledFunctions.size(); }
195 // Subscripting operator - Return the i'th called function...
197 CallGraphNode *operator[](unsigned i) const {
198 return CalledFunctions[i].second;
201 /// dump - Print out this call graph node.
204 void print(llvm_ostream &OS) const {
205 if (OS.stream()) print(*OS.stream());
207 void print(std::ostream &OS) const;
209 //===---------------------------------------------------------------------
210 // Methods to keep a call graph up to date with a function that has been
214 /// removeAllCalledFunctions - As the name implies, this removes all edges
215 /// from this CallGraphNode to any functions it calls.
216 void removeAllCalledFunctions() {
217 CalledFunctions.clear();
220 /// addCalledFunction add a function to the list of functions called by this
222 void addCalledFunction(CallSite CS, CallGraphNode *M) {
223 CalledFunctions.push_back(std::make_pair(CS, M));
226 /// removeCallEdgeTo - This method removes a *single* edge to the specified
227 /// callee function. Note that this method takes linear time, so it should be
229 void removeCallEdgeTo(CallGraphNode *Callee);
231 /// removeAnyCallEdgeTo - This method removes any call edges from this node to
232 /// the specified callee function. This takes more time to execute than
233 /// removeCallEdgeTo, so it should not be used unless necessary.
234 void removeAnyCallEdgeTo(CallGraphNode *Callee);
236 friend class CallGraph;
238 // CallGraphNode ctor - Create a node for the specified function.
239 inline CallGraphNode(Function *f) : F(f) {}
242 //===----------------------------------------------------------------------===//
243 // GraphTraits specializations for call graphs so that they can be treated as
244 // graphs by the generic graph algorithms.
247 // Provide graph traits for tranversing call graphs using standard graph
249 template <> struct GraphTraits<CallGraphNode*> {
250 typedef CallGraphNode NodeType;
252 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy;
253 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
255 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
257 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
259 static inline ChildIteratorType child_begin(NodeType *N) {
260 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
262 static inline ChildIteratorType child_end (NodeType *N) {
263 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
266 static CallGraphNode *CGNDeref(CGNPairTy P) {
272 template <> struct GraphTraits<const CallGraphNode*> {
273 typedef const CallGraphNode NodeType;
274 typedef NodeType::const_iterator ChildIteratorType;
276 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
277 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
278 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
281 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
282 static NodeType *getEntryNode(CallGraph *CGN) {
283 return CGN->getExternalCallingNode(); // Start at the external node!
285 typedef std::pair<const Function*, CallGraphNode*> PairTy;
286 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
288 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
289 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
290 static nodes_iterator nodes_begin(CallGraph *CG) {
291 return map_iterator(CG->begin(), DerefFun(CGdereference));
293 static nodes_iterator nodes_end (CallGraph *CG) {
294 return map_iterator(CG->end(), DerefFun(CGdereference));
297 static CallGraphNode &CGdereference(PairTy P) {
302 template<> struct GraphTraits<const CallGraph*> :
303 public GraphTraits<const CallGraphNode*> {
304 static NodeType *getEntryNode(const CallGraph *CGN) {
305 return CGN->getExternalCallingNode();
307 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
308 typedef CallGraph::const_iterator nodes_iterator;
309 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
310 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
313 } // End llvm namespace
315 // Make sure that any clients of this file link in CallGraph.cpp
316 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)