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/Support/ValueHandle.h"
59 #include "llvm/System/IncludeFile.h"
68 //===----------------------------------------------------------------------===//
69 // CallGraph class definition
73 Module *Mod; // The module this call graph represents
75 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
76 FunctionMapTy FunctionMap; // Map from a function to its node
79 static char ID; // Class identification, replacement for typeinfo
80 //===---------------------------------------------------------------------
83 typedef FunctionMapTy::iterator iterator;
84 typedef FunctionMapTy::const_iterator const_iterator;
86 /// getModule - Return the module the call graph corresponds to.
88 Module &getModule() const { return *Mod; }
90 inline iterator begin() { return FunctionMap.begin(); }
91 inline iterator end() { return FunctionMap.end(); }
92 inline const_iterator begin() const { return FunctionMap.begin(); }
93 inline const_iterator end() const { return FunctionMap.end(); }
95 // Subscripting operators, return the call graph node for the provided
97 inline const CallGraphNode *operator[](const Function *F) const {
98 const_iterator I = FunctionMap.find(F);
99 assert(I != FunctionMap.end() && "Function not in callgraph!");
102 inline CallGraphNode *operator[](const Function *F) {
103 const_iterator I = FunctionMap.find(F);
104 assert(I != FunctionMap.end() && "Function not in callgraph!");
108 /// Returns the CallGraphNode which is used to represent undetermined calls
109 /// into the callgraph. Override this if you want behavioral inheritance.
110 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
111 virtual CallGraphNode* getCallsExternalNode() const { return 0; }
113 /// Return the root/main method in the module, or some other root node, such
114 /// as the externalcallingnode. Overload these if you behavioral
116 virtual CallGraphNode* getRoot() { return 0; }
117 virtual const CallGraphNode* getRoot() const { return 0; }
119 //===---------------------------------------------------------------------
120 // Functions to keep a call graph up to date with a function that has been
124 /// removeFunctionFromModule - Unlink the function from this module, returning
125 /// it. Because this removes the function from the module, the call graph
126 /// node is destroyed. This is only valid if the function does not call any
127 /// other functions (ie, there are no edges in it's CGN). The easiest way to
128 /// do this is to dropAllReferences before calling this.
130 Function *removeFunctionFromModule(CallGraphNode *CGN);
131 Function *removeFunctionFromModule(Function *F) {
132 return removeFunctionFromModule((*this)[F]);
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 void print(raw_ostream &o, Module *) const;
157 // destroy - Release memory for the call graph
158 virtual void destroy();
161 //===----------------------------------------------------------------------===//
162 // CallGraphNode class definition.
164 class CallGraphNode {
165 AssertingVH<Function> F;
167 // CallRecord - This is a pair of the calling instruction (a call or invoke)
168 // and the callgraph node being called.
170 typedef std::pair<WeakVH, CallGraphNode*> CallRecord;
172 std::vector<CallRecord> CalledFunctions;
174 /// NumReferences - This is the number of times that this CallGraphNode occurs
175 /// in the CalledFunctions array of this or other CallGraphNodes.
176 unsigned NumReferences;
178 CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT
179 void operator=(const CallGraphNode &); // DO NOT IMPLEMENT
181 void DropRef() { --NumReferences; }
182 void AddRef() { ++NumReferences; }
184 typedef std::vector<CallRecord> CalledFunctionsVector;
187 // CallGraphNode ctor - Create a node for the specified function.
188 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {}
190 //===---------------------------------------------------------------------
194 typedef std::vector<CallRecord>::iterator iterator;
195 typedef std::vector<CallRecord>::const_iterator const_iterator;
197 // getFunction - Return the function that this call graph node represents.
198 Function *getFunction() const { return F; }
200 inline iterator begin() { return CalledFunctions.begin(); }
201 inline iterator end() { return CalledFunctions.end(); }
202 inline const_iterator begin() const { return CalledFunctions.begin(); }
203 inline const_iterator end() const { return CalledFunctions.end(); }
204 inline bool empty() const { return CalledFunctions.empty(); }
205 inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
207 /// getNumReferences - Return the number of other CallGraphNodes in this
208 /// CallGraph that reference this node in their callee list.
209 unsigned getNumReferences() const { return NumReferences; }
211 // Subscripting operator - Return the i'th called function.
213 CallGraphNode *operator[](unsigned i) const {
214 assert(i < CalledFunctions.size() && "Invalid index");
215 return CalledFunctions[i].second;
218 /// dump - Print out this call graph node.
221 void print(raw_ostream &OS) const;
223 //===---------------------------------------------------------------------
224 // Methods to keep a call graph up to date with a function that has been
228 /// removeAllCalledFunctions - As the name implies, this removes all edges
229 /// from this CallGraphNode to any functions it calls.
230 void removeAllCalledFunctions() {
231 while (!CalledFunctions.empty()) {
232 CalledFunctions.back().second->DropRef();
233 CalledFunctions.pop_back();
237 /// stealCalledFunctionsFrom - Move all the callee information from N to this
239 void stealCalledFunctionsFrom(CallGraphNode *N) {
240 assert(CalledFunctions.empty() &&
241 "Cannot steal callsite information if I already have some");
242 std::swap(CalledFunctions, N->CalledFunctions);
246 /// addCalledFunction - Add a function to the list of functions called by this
248 void addCalledFunction(CallSite CS, CallGraphNode *M) {
249 CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M));
253 void removeCallEdge(iterator I) {
254 I->second->DropRef();
255 *I = CalledFunctions.back();
256 CalledFunctions.pop_back();
260 /// removeCallEdgeFor - This method removes the edge in the node for the
261 /// specified call site. Note that this method takes linear time, so it
262 /// should be used sparingly.
263 void removeCallEdgeFor(CallSite CS);
265 /// removeAnyCallEdgeTo - This method removes all call edges from this node
266 /// to the specified callee function. This takes more time to execute than
267 /// removeCallEdgeTo, so it should not be used unless necessary.
268 void removeAnyCallEdgeTo(CallGraphNode *Callee);
270 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
271 /// from this node to the specified callee function.
272 void removeOneAbstractEdgeTo(CallGraphNode *Callee);
275 //===----------------------------------------------------------------------===//
276 // GraphTraits specializations for call graphs so that they can be treated as
277 // graphs by the generic graph algorithms.
280 // Provide graph traits for tranversing call graphs using standard graph
282 template <> struct GraphTraits<CallGraphNode*> {
283 typedef CallGraphNode NodeType;
285 typedef CallGraphNode::CallRecord CGNPairTy;
286 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
288 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
290 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
292 static inline ChildIteratorType child_begin(NodeType *N) {
293 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
295 static inline ChildIteratorType child_end (NodeType *N) {
296 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
299 static CallGraphNode *CGNDeref(CGNPairTy P) {
305 template <> struct GraphTraits<const CallGraphNode*> {
306 typedef const CallGraphNode NodeType;
307 typedef NodeType::const_iterator ChildIteratorType;
309 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
310 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
311 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
314 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
315 static NodeType *getEntryNode(CallGraph *CGN) {
316 return CGN->getExternalCallingNode(); // Start at the external node!
318 typedef std::pair<const Function*, CallGraphNode*> PairTy;
319 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
321 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
322 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
323 static nodes_iterator nodes_begin(CallGraph *CG) {
324 return map_iterator(CG->begin(), DerefFun(CGdereference));
326 static nodes_iterator nodes_end (CallGraph *CG) {
327 return map_iterator(CG->end(), DerefFun(CGdereference));
330 static CallGraphNode &CGdereference(PairTy P) {
335 template<> struct GraphTraits<const CallGraph*> :
336 public GraphTraits<const CallGraphNode*> {
337 static NodeType *getEntryNode(const CallGraph *CGN) {
338 return CGN->getExternalCallingNode();
340 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
341 typedef CallGraph::const_iterator nodes_iterator;
342 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
343 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
346 } // End llvm namespace
348 // Make sure that any clients of this file link in CallGraph.cpp
349 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)