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"
58 #include "llvm/System/IncludeFile.h"
67 //===----------------------------------------------------------------------===//
68 // CallGraph class definition
72 Module *Mod; // The module this call graph represents
74 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
75 FunctionMapTy FunctionMap; // Map from a function to its node
78 static char ID; // Class identification, replacement for typeinfo
79 //===---------------------------------------------------------------------
82 typedef FunctionMapTy::iterator iterator;
83 typedef FunctionMapTy::const_iterator const_iterator;
85 /// getModule - Return the module the call graph corresponds to.
87 Module &getModule() const { return *Mod; }
89 inline iterator begin() { return FunctionMap.begin(); }
90 inline iterator end() { return FunctionMap.end(); }
91 inline const_iterator begin() const { return FunctionMap.begin(); }
92 inline const_iterator end() const { return FunctionMap.end(); }
94 // Subscripting operators, return the call graph node for the provided
96 inline const CallGraphNode *operator[](const Function *F) const {
97 const_iterator I = FunctionMap.find(F);
98 assert(I != FunctionMap.end() && "Function not in callgraph!");
101 inline CallGraphNode *operator[](const Function *F) {
102 const_iterator I = FunctionMap.find(F);
103 assert(I != FunctionMap.end() && "Function not in callgraph!");
107 /// Returns the CallGraphNode which is used to represent undetermined calls
108 /// into the callgraph. Override this if you want behavioral inheritance.
109 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
111 /// Return the root/main method in the module, or some other root node, such
112 /// as the externalcallingnode. Overload these if you behavioral
114 virtual CallGraphNode* getRoot() { return 0; }
115 virtual const CallGraphNode* getRoot() const { return 0; }
117 //===---------------------------------------------------------------------
118 // Functions to keep a call graph up to date with a function that has been
122 /// removeFunctionFromModule - Unlink the function from this module, returning
123 /// it. Because this removes the function from the module, the call graph
124 /// node is destroyed. This is only valid if the function does not call any
125 /// other functions (ie, there are no edges in it's CGN). The easiest way to
126 /// do this is to dropAllReferences before calling this.
128 Function *removeFunctionFromModule(CallGraphNode *CGN);
129 Function *removeFunctionFromModule(Function *F) {
130 return removeFunctionFromModule((*this)[F]);
133 /// changeFunction - This method changes the function associated with this
134 /// CallGraphNode, for use by transformations that need to change the
135 /// prototype of a Function (thus they must create a new Function and move the
137 void changeFunction(Function *OldF, Function *NewF);
139 /// getOrInsertFunction - This method is identical to calling operator[], but
140 /// it will insert a new CallGraphNode for the specified function if one does
141 /// not already exist.
142 CallGraphNode *getOrInsertFunction(const Function *F);
144 //===---------------------------------------------------------------------
145 // Pass infrastructure interface glue code...
151 virtual ~CallGraph() { destroy(); }
153 /// initialize - Call this method before calling other methods,
154 /// re/initializes the state of the CallGraph.
156 void initialize(Module &M);
158 void print(raw_ostream &o, Module *) const;
161 // destroy - Release memory for the call graph
162 virtual void destroy();
165 //===----------------------------------------------------------------------===//
166 // CallGraphNode class definition
168 class CallGraphNode {
170 typedef std::pair<CallSite,CallGraphNode*> CallRecord;
171 std::vector<CallRecord> CalledFunctions;
173 CallGraphNode(const CallGraphNode &); // Do not implement
175 typedef std::vector<CallRecord> CalledFunctionsVector;
177 //===---------------------------------------------------------------------
178 // Accessor methods...
181 typedef std::vector<CallRecord>::iterator iterator;
182 typedef std::vector<CallRecord>::const_iterator const_iterator;
184 // getFunction - Return the function that this call graph node represents...
185 Function *getFunction() const { return F; }
187 inline iterator begin() { return CalledFunctions.begin(); }
188 inline iterator end() { return CalledFunctions.end(); }
189 inline const_iterator begin() const { return CalledFunctions.begin(); }
190 inline const_iterator end() const { return CalledFunctions.end(); }
191 inline bool empty() const { return CalledFunctions.empty(); }
192 inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
194 // Subscripting operator - Return the i'th called function...
196 CallGraphNode *operator[](unsigned i) const {
197 return CalledFunctions[i].second;
200 /// dump - Print out this call graph node.
203 void print(raw_ostream &OS) const;
205 //===---------------------------------------------------------------------
206 // Methods to keep a call graph up to date with a function that has been
210 /// removeAllCalledFunctions - As the name implies, this removes all edges
211 /// from this CallGraphNode to any functions it calls.
212 void removeAllCalledFunctions() {
213 CalledFunctions.clear();
216 /// addCalledFunction - Add a function to the list of functions called by this
218 void addCalledFunction(CallSite CS, CallGraphNode *M) {
219 CalledFunctions.push_back(std::make_pair(CS, M));
222 /// removeCallEdgeFor - This method removes the edge in the node for the
223 /// specified call site. Note that this method takes linear time, so it
224 /// should be used sparingly.
225 void removeCallEdgeFor(CallSite CS);
227 /// removeAnyCallEdgeTo - This method removes all call edges from this node
228 /// to the specified callee function. This takes more time to execute than
229 /// removeCallEdgeTo, so it should not be used unless necessary.
230 void removeAnyCallEdgeTo(CallGraphNode *Callee);
232 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
233 /// from this node to the specified callee function.
234 void removeOneAbstractEdgeTo(CallGraphNode *Callee);
236 /// replaceCallSite - Make the edge in the node for Old CallSite be for
237 /// New CallSite instead. Note that this method takes linear time, so it
238 /// should be used sparingly.
239 void replaceCallSite(CallSite Old, CallSite New);
241 friend class CallGraph;
243 // CallGraphNode ctor - Create a node for the specified function.
244 inline CallGraphNode(Function *f) : F(f) {}
247 //===----------------------------------------------------------------------===//
248 // GraphTraits specializations for call graphs so that they can be treated as
249 // graphs by the generic graph algorithms.
252 // Provide graph traits for tranversing call graphs using standard graph
254 template <> struct GraphTraits<CallGraphNode*> {
255 typedef CallGraphNode NodeType;
257 typedef std::pair<CallSite, CallGraphNode*> CGNPairTy;
258 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
260 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
262 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
264 static inline ChildIteratorType child_begin(NodeType *N) {
265 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
267 static inline ChildIteratorType child_end (NodeType *N) {
268 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
271 static CallGraphNode *CGNDeref(CGNPairTy P) {
277 template <> struct GraphTraits<const CallGraphNode*> {
278 typedef const CallGraphNode NodeType;
279 typedef NodeType::const_iterator ChildIteratorType;
281 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
282 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
283 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
286 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
287 static NodeType *getEntryNode(CallGraph *CGN) {
288 return CGN->getExternalCallingNode(); // Start at the external node!
290 typedef std::pair<const Function*, CallGraphNode*> PairTy;
291 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
293 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
294 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
295 static nodes_iterator nodes_begin(CallGraph *CG) {
296 return map_iterator(CG->begin(), DerefFun(CGdereference));
298 static nodes_iterator nodes_end (CallGraph *CG) {
299 return map_iterator(CG->end(), DerefFun(CGdereference));
302 static CallGraphNode &CGdereference(PairTy P) {
307 template<> struct GraphTraits<const CallGraph*> :
308 public GraphTraits<const CallGraphNode*> {
309 static NodeType *getEntryNode(const CallGraph *CGN) {
310 return CGN->getExternalCallingNode();
312 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
313 typedef CallGraph::const_iterator nodes_iterator;
314 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
315 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
318 } // End llvm namespace
320 // Make sure that any clients of this file link in CallGraph.cpp
321 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)