1 //===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // 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 static char ID; // Class identification, replacement for typeinfo
77 //===---------------------------------------------------------------------
80 typedef FunctionMapTy::iterator iterator;
81 typedef FunctionMapTy::const_iterator const_iterator;
83 /// getModule - Return the module the call graph corresponds to.
85 Module &getModule() const { return *Mod; }
87 inline iterator begin() { return FunctionMap.begin(); }
88 inline iterator end() { return FunctionMap.end(); }
89 inline const_iterator begin() const { return FunctionMap.begin(); }
90 inline const_iterator end() const { return FunctionMap.end(); }
92 // Subscripting operators, return the call graph node for the provided
94 inline const CallGraphNode *operator[](const Function *F) const {
95 const_iterator I = FunctionMap.find(F);
96 assert(I != FunctionMap.end() && "Function not in callgraph!");
99 inline CallGraphNode *operator[](const Function *F) {
100 const_iterator I = FunctionMap.find(F);
101 assert(I != FunctionMap.end() && "Function not in callgraph!");
105 //Returns the CallGraphNode which is used to represent undetermined calls
106 // into the callgraph. Override this if you want behavioural inheritance.
107 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
109 //Return the root/main method in the module, or some other root node, such
110 // as the externalcallingnode. Overload these if you behavioural
112 virtual CallGraphNode* getRoot() { return 0; }
113 virtual const CallGraphNode* getRoot() const { return 0; }
115 //===---------------------------------------------------------------------
116 // Functions to keep a call graph up to date with a function that has been
120 /// removeFunctionFromModule - Unlink the function from this module, returning
121 /// it. Because this removes the function from the module, the call graph
122 /// node is destroyed. This is only valid if the function does not call any
123 /// other functions (ie, there are no edges in it's CGN). The easiest way to
124 /// do this is to dropAllReferences before calling this.
126 Function *removeFunctionFromModule(CallGraphNode *CGN);
127 Function *removeFunctionFromModule(Function *F) {
128 return removeFunctionFromModule((*this)[F]);
131 /// changeFunction - This method changes the function associated with this
132 /// CallGraphNode, for use by transformations that need to change the
133 /// prototype of a Function (thus they must create a new Function and move the
135 void changeFunction(Function *OldF, Function *NewF);
137 /// getOrInsertFunction - This method is identical to calling operator[], but
138 /// it will insert a new CallGraphNode for the specified function if one does
139 /// not already exist.
140 CallGraphNode *getOrInsertFunction(const Function *F);
142 //===---------------------------------------------------------------------
143 // Pass infrastructure interface glue code...
149 virtual ~CallGraph() { destroy(); }
151 /// initialize - Call this method before calling other methods,
152 /// re/initializes the state of the CallGraph.
154 void initialize(Module &M);
156 virtual void print(std::ostream &o, const Module *M) const;
157 void print(std::ostream *o, const Module *M) const { if (o) print(*o, M); }
160 // stub - dummy function, just ignore it
164 // destroy - Release memory for the call graph
165 virtual void destroy();
168 //===----------------------------------------------------------------------===//
169 // CallGraphNode class definition
171 class CallGraphNode {
173 typedef std::pair<CallSite,CallGraphNode*> CallRecord;
174 std::vector<CallRecord> CalledFunctions;
176 CallGraphNode(const CallGraphNode &); // Do not implement
178 //===---------------------------------------------------------------------
179 // Accessor methods...
182 typedef std::vector<CallRecord>::iterator iterator;
183 typedef std::vector<CallRecord>::const_iterator const_iterator;
185 // getFunction - Return the function that this call graph node represents...
186 Function *getFunction() const { return F; }
188 inline iterator begin() { return CalledFunctions.begin(); }
189 inline iterator end() { return CalledFunctions.end(); }
190 inline const_iterator begin() const { return CalledFunctions.begin(); }
191 inline const_iterator end() const { return CalledFunctions.end(); }
192 inline bool empty() const { return CalledFunctions.empty(); }
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(std::ostream &OS) const;
205 void print(std::ostream *OS) const { if (OS) print(*OS); }
207 //===---------------------------------------------------------------------
208 // Methods to keep a call graph up to date with a function that has been
212 /// removeAllCalledFunctions - As the name implies, this removes all edges
213 /// from this CallGraphNode to any functions it calls.
214 void removeAllCalledFunctions() {
215 CalledFunctions.clear();
218 /// addCalledFunction add a function to the list of functions called by this
220 void addCalledFunction(CallSite CS, CallGraphNode *M) {
221 CalledFunctions.push_back(std::make_pair(CS, M));
224 /// removeCallEdgeTo - This method removes a *single* edge to the specified
225 /// callee function. Note that this method takes linear time, so it should be
227 void removeCallEdgeTo(CallGraphNode *Callee);
229 /// removeAnyCallEdgeTo - This method removes any call edges from this node to
230 /// the specified callee function. This takes more time to execute than
231 /// removeCallEdgeTo, so it should not be used unless necessary.
232 void removeAnyCallEdgeTo(CallGraphNode *Callee);
234 friend class CallGraph;
236 // CallGraphNode ctor - Create a node for the specified function.
237 inline CallGraphNode(Function *f) : F(f) {}
240 //===----------------------------------------------------------------------===//
241 // GraphTraits specializations for call graphs so that they can be treated as
242 // graphs by the generic graph algorithms.
245 // Provide graph traits for tranversing call graphs using standard graph
247 template <> struct GraphTraits<CallGraphNode*> {
248 typedef CallGraphNode NodeType;
250 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy;
251 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
253 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
255 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
257 static inline ChildIteratorType child_begin(NodeType *N) {
258 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
260 static inline ChildIteratorType child_end (NodeType *N) {
261 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
264 static CallGraphNode *CGNDeref(CGNPairTy P) {
270 template <> struct GraphTraits<const CallGraphNode*> {
271 typedef const CallGraphNode NodeType;
272 typedef NodeType::const_iterator ChildIteratorType;
274 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
275 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
276 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
279 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
280 static NodeType *getEntryNode(CallGraph *CGN) {
281 return CGN->getExternalCallingNode(); // Start at the external node!
283 typedef std::pair<const Function*, CallGraphNode*> PairTy;
284 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
286 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
287 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
288 static nodes_iterator nodes_begin(CallGraph *CG) {
289 return map_iterator(CG->begin(), DerefFun(CGdereference));
291 static nodes_iterator nodes_end (CallGraph *CG) {
292 return map_iterator(CG->end(), DerefFun(CGdereference));
295 static CallGraphNode &CGdereference(PairTy P) {
300 template<> struct GraphTraits<const CallGraph*> :
301 public GraphTraits<const CallGraphNode*> {
302 static NodeType *getEntryNode(const CallGraph *CGN) {
303 return CGN->getExternalCallingNode();
305 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
306 typedef CallGraph::const_iterator nodes_iterator;
307 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
308 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
311 } // End llvm namespace
313 // Make sure that any clients of this file link in CallGraph.cpp
314 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)