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 will contain nodes where the function that they correspond to is
18 // null. This 'external' node is used to represent control flow that is not
19 // represented (or analyzable) in the module. As such, the external node will
20 // have edges to functions with the following properties:
21 // 1. All functions in the module without internal linkage, since they could
22 // be called by functions outside of the our analysis capability.
23 // 2. All functions whose address is used for something more than a direct
24 // call, for example being stored into a memory location. Since they may
25 // be called by an unknown caller later, they must be tracked as such.
27 // Similarly, functions have a call edge to the external node iff:
28 // 1. The function is external, reflecting the fact that they could call
29 // anything without internal linkage or that has its address taken.
30 // 2. The function contains an indirect function call.
32 // As an extension in the future, there may be multiple nodes with a null
33 // function. These will be used when we can prove (through pointer analysis)
34 // that an indirect call site can call only a specific set of functions.
36 // Because of these properties, the CallGraph captures a conservative superset
37 // of all of the caller-callee relationships, which is useful for
40 // The CallGraph class also attempts to figure out what the root of the
41 // CallGraph is, which is currently does by looking for a function named 'main'.
42 // If no function named 'main' is found, the external node is used as the entry
43 // node, reflecting the fact that any function without internal linkage could
44 // be called into (which is common for libraries).
46 //===----------------------------------------------------------------------===//
48 #ifndef LLVM_ANALYSIS_CALLGRAPH_H
49 #define LLVM_ANALYSIS_CALLGRAPH_H
51 #include "Support/GraphTraits.h"
52 #include "Support/STLExtras.h"
53 #include "llvm/Pass.h"
61 //===----------------------------------------------------------------------===//
62 // CallGraph class definition
64 class CallGraph : public Pass {
65 Module *Mod; // The module this call graph represents
67 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
68 FunctionMapTy FunctionMap; // Map from a function to its node
70 // Root is root of the call graph, or the external node if a 'main' function
71 // couldn't be found. ExternalNode is equivalent to (*this)[0].
73 CallGraphNode *Root, *ExternalNode;
76 //===---------------------------------------------------------------------
79 typedef FunctionMapTy::iterator iterator;
80 typedef FunctionMapTy::const_iterator const_iterator;
82 // getExternalNode - Return the node that points to all functions that are
83 // accessable from outside of the current program.
85 CallGraphNode *getExternalNode() { return ExternalNode; }
86 const CallGraphNode *getExternalNode() const { return ExternalNode; }
88 // getRoot - Return the root of the call graph, which is either main, or if
89 // main cannot be found, the external node.
91 CallGraphNode *getRoot() { return Root; }
92 const CallGraphNode *getRoot() const { return Root; }
94 inline iterator begin() { return FunctionMap.begin(); }
95 inline iterator end() { return FunctionMap.end(); }
96 inline const_iterator begin() const { return FunctionMap.begin(); }
97 inline const_iterator end() const { return FunctionMap.end(); }
100 // Subscripting operators, return the call graph node for the provided
102 inline const CallGraphNode *operator[](const Function *F) const {
103 const_iterator I = FunctionMap.find(F);
104 assert(I != FunctionMap.end() && "Function not in callgraph!");
107 inline CallGraphNode *operator[](const Function *F) {
108 const_iterator I = FunctionMap.find(F);
109 assert(I != FunctionMap.end() && "Function not in callgraph!");
113 //===---------------------------------------------------------------------
114 // Functions to keep a call graph up to date with a function that has been
117 void addFunctionToModule(Function *F);
120 // removeFunctionFromModule - Unlink the function from this module, returning
121 // it. Because this removes the function from the module, the call graph node
122 // is destroyed. This is only valid if the function does not call any other
123 // functions (ie, there are no edges in it's CGN). The easiest way to do this
124 // is to dropAllReferences before calling this.
126 Function *removeFunctionFromModule(CallGraphNode *CGN);
127 Function *removeFunctionFromModule(Function *F) {
128 return removeFunctionFromModule((*this)[F]);
132 //===---------------------------------------------------------------------
133 // Pass infrastructure interface glue code...
135 CallGraph() : Root(0) {}
136 ~CallGraph() { destroy(); }
138 // run - Compute the call graph for the specified module.
139 virtual bool run(Module &M);
141 // getAnalysisUsage - This obviously provides a call graph
142 virtual void getAnalysisUsage(AnalysisUsage &AU) const {
143 AU.setPreservesAll();
146 // releaseMemory - Data structures can be large, so free memory aggressively.
147 virtual void releaseMemory() {
151 /// Print the types found in the module. If the optional Module parameter is
152 /// passed in, then the types are printed symbolically if possible, using the
153 /// symbol table from the module.
155 void print(std::ostream &o, const Module *M) const;
157 // stub - dummy function, just ignore it
160 //===---------------------------------------------------------------------
161 // Implementation of CallGraph construction
164 // getNodeFor - Return the node for the specified function or create one if it
165 // does not already exist.
167 CallGraphNode *getNodeFor(Function *F);
169 // addToCallGraph - Add a function to the call graph, and link the node to all
170 // of the functions that it calls.
172 void addToCallGraph(Function *F);
174 // destroy - Release memory for the call graph
179 //===----------------------------------------------------------------------===//
180 // CallGraphNode class definition
182 class CallGraphNode {
184 std::vector<CallGraphNode*> CalledFunctions;
186 CallGraphNode(const CallGraphNode &); // Do not implement
188 //===---------------------------------------------------------------------
189 // Accessor methods...
192 typedef std::vector<CallGraphNode*>::iterator iterator;
193 typedef std::vector<CallGraphNode*>::const_iterator const_iterator;
195 // getFunction - Return the function that this call graph node represents...
196 Function *getFunction() const { return F; }
198 inline iterator begin() { return CalledFunctions.begin(); }
199 inline iterator end() { return CalledFunctions.end(); }
200 inline const_iterator begin() const { return CalledFunctions.begin(); }
201 inline const_iterator end() const { return CalledFunctions.end(); }
202 inline unsigned size() const { return CalledFunctions.size(); }
204 // Subscripting operator - Return the i'th called function...
206 CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];}
209 //===---------------------------------------------------------------------
210 // Methods to keep a call graph up to date with a function that has been
214 void removeAllCalledFunctions() {
215 CalledFunctions.clear();
218 private: // Stuff to construct the node, used by CallGraph
219 friend class CallGraph;
221 // CallGraphNode ctor - Create a node for the specified function...
222 inline CallGraphNode(Function *f) : F(f) {}
224 // addCalledFunction add a function to the list of functions called by this
226 void addCalledFunction(CallGraphNode *M) {
227 CalledFunctions.push_back(M);
233 //===----------------------------------------------------------------------===//
234 // GraphTraits specializations for call graphs so that they can be treated as
235 // graphs by the generic graph algorithms...
238 // Provide graph traits for tranversing call graphs using standard graph
240 template <> struct GraphTraits<CallGraphNode*> {
241 typedef CallGraphNode NodeType;
242 typedef NodeType::iterator ChildIteratorType;
244 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
245 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
246 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
249 template <> struct GraphTraits<const CallGraphNode*> {
250 typedef const CallGraphNode NodeType;
251 typedef NodeType::const_iterator ChildIteratorType;
253 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
254 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
255 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
258 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
259 static NodeType *getEntryNode(CallGraph *CGN) {
260 return CGN->getExternalNode(); // Start at the external node!
262 typedef std::pair<const Function*, CallGraphNode*> PairTy;
263 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
265 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
266 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
267 static nodes_iterator nodes_begin(CallGraph *CG) {
268 return map_iterator(CG->begin(), DerefFun(CGdereference));
270 static nodes_iterator nodes_end (CallGraph *CG) {
271 return map_iterator(CG->end(), DerefFun(CGdereference));
274 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->getExternalNode();
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 // Make sure that any clients of this file link in PostDominators.cpp
292 CALLGRAPH_INCLUDE_FILE((void*)&CallGraph::stub);
294 } // End llvm namespace