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/IR/Function.h"
57 #include "llvm/Pass.h"
58 #include "llvm/Support/CallSite.h"
59 #include "llvm/Support/IncludeFile.h"
60 #include "llvm/Support/ValueHandle.h"
69 //===----------------------------------------------------------------------===//
70 // CallGraph class definition
74 Module *Mod; // The module this call graph represents
76 typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
77 FunctionMapTy FunctionMap; // Map from a function to its node
80 static char ID; // Class identification, replacement for typeinfo
81 //===---------------------------------------------------------------------
84 typedef FunctionMapTy::iterator iterator;
85 typedef FunctionMapTy::const_iterator const_iterator;
87 /// getModule - Return the module the call graph corresponds to.
89 Module &getModule() const { return *Mod; }
91 inline iterator begin() { return FunctionMap.begin(); }
92 inline iterator end() { return FunctionMap.end(); }
93 inline const_iterator begin() const { return FunctionMap.begin(); }
94 inline const_iterator end() const { return FunctionMap.end(); }
96 // Subscripting operators, return the call graph node for the provided
98 inline const CallGraphNode *operator[](const Function *F) const {
99 const_iterator I = FunctionMap.find(F);
100 assert(I != FunctionMap.end() && "Function not in callgraph!");
103 inline CallGraphNode *operator[](const Function *F) {
104 const_iterator I = FunctionMap.find(F);
105 assert(I != FunctionMap.end() && "Function not in callgraph!");
109 /// Returns the CallGraphNode which is used to represent undetermined calls
110 /// into the callgraph. Override this if you want behavioral inheritance.
111 virtual CallGraphNode* getExternalCallingNode() const { return 0; }
112 virtual CallGraphNode* getCallsExternalNode() const { return 0; }
114 /// Return the root/main method in the module, or some other root node, such
115 /// as the externalcallingnode. Overload these if you behavioral
117 virtual CallGraphNode* getRoot() { return 0; }
118 virtual const CallGraphNode* getRoot() const { return 0; }
120 //===---------------------------------------------------------------------
121 // Functions to keep a call graph up to date with a function that has been
125 /// removeFunctionFromModule - Unlink the function from this module, returning
126 /// it. Because this removes the function from the module, the call graph
127 /// node is destroyed. This is only valid if the function does not call any
128 /// other functions (ie, there are no edges in it's CGN). The easiest way to
129 /// do this is to dropAllReferences before calling this.
131 Function *removeFunctionFromModule(CallGraphNode *CGN);
132 Function *removeFunctionFromModule(Function *F) {
133 return removeFunctionFromModule((*this)[F]);
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 /// spliceFunction - Replace the function represented by this node by another.
142 /// This does not rescan the body of the function, so it is suitable when
143 /// splicing the body of one function to another while also updating all
144 /// callers from the old function to the new.
146 void spliceFunction(const Function *From, const Function *To);
148 //===---------------------------------------------------------------------
149 // Pass infrastructure interface glue code.
155 virtual ~CallGraph() { destroy(); }
157 /// initialize - Call this method before calling other methods,
158 /// re/initializes the state of the CallGraph.
160 void initialize(Module &M);
162 void print(raw_ostream &o, Module *) const;
165 // destroy - Release memory for the call graph
166 virtual void destroy();
169 //===----------------------------------------------------------------------===//
170 // CallGraphNode class definition.
172 class CallGraphNode {
173 friend class CallGraph;
175 AssertingVH<Function> F;
177 // CallRecord - This is a pair of the calling instruction (a call or invoke)
178 // and the callgraph node being called.
180 typedef std::pair<WeakVH, CallGraphNode*> CallRecord;
182 std::vector<CallRecord> CalledFunctions;
184 /// NumReferences - This is the number of times that this CallGraphNode occurs
185 /// in the CalledFunctions array of this or other CallGraphNodes.
186 unsigned NumReferences;
188 CallGraphNode(const CallGraphNode &) LLVM_DELETED_FUNCTION;
189 void operator=(const CallGraphNode &) LLVM_DELETED_FUNCTION;
191 void DropRef() { --NumReferences; }
192 void AddRef() { ++NumReferences; }
194 typedef std::vector<CallRecord> CalledFunctionsVector;
197 // CallGraphNode ctor - Create a node for the specified function.
198 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {}
200 assert(NumReferences == 0 && "Node deleted while references remain");
203 //===---------------------------------------------------------------------
207 typedef std::vector<CallRecord>::iterator iterator;
208 typedef std::vector<CallRecord>::const_iterator const_iterator;
210 // getFunction - Return the function that this call graph node represents.
211 Function *getFunction() const { return F; }
213 inline iterator begin() { return CalledFunctions.begin(); }
214 inline iterator end() { return CalledFunctions.end(); }
215 inline const_iterator begin() const { return CalledFunctions.begin(); }
216 inline const_iterator end() const { return CalledFunctions.end(); }
217 inline bool empty() const { return CalledFunctions.empty(); }
218 inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
220 /// getNumReferences - Return the number of other CallGraphNodes in this
221 /// CallGraph that reference this node in their callee list.
222 unsigned getNumReferences() const { return NumReferences; }
224 // Subscripting operator - Return the i'th called function.
226 CallGraphNode *operator[](unsigned i) const {
227 assert(i < CalledFunctions.size() && "Invalid index");
228 return CalledFunctions[i].second;
231 /// dump - Print out this call graph node.
234 void print(raw_ostream &OS) const;
236 //===---------------------------------------------------------------------
237 // Methods to keep a call graph up to date with a function that has been
241 /// removeAllCalledFunctions - As the name implies, this removes all edges
242 /// from this CallGraphNode to any functions it calls.
243 void removeAllCalledFunctions() {
244 while (!CalledFunctions.empty()) {
245 CalledFunctions.back().second->DropRef();
246 CalledFunctions.pop_back();
250 /// stealCalledFunctionsFrom - Move all the callee information from N to this
252 void stealCalledFunctionsFrom(CallGraphNode *N) {
253 assert(CalledFunctions.empty() &&
254 "Cannot steal callsite information if I already have some");
255 std::swap(CalledFunctions, N->CalledFunctions);
259 /// addCalledFunction - Add a function to the list of functions called by this
261 void addCalledFunction(CallSite CS, CallGraphNode *M) {
262 assert(!CS.getInstruction() ||
263 !CS.getCalledFunction() ||
264 !CS.getCalledFunction()->isIntrinsic());
265 CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M));
269 void removeCallEdge(iterator I) {
270 I->second->DropRef();
271 *I = CalledFunctions.back();
272 CalledFunctions.pop_back();
276 /// removeCallEdgeFor - This method removes the edge in the node for the
277 /// specified call site. Note that this method takes linear time, so it
278 /// should be used sparingly.
279 void removeCallEdgeFor(CallSite CS);
281 /// removeAnyCallEdgeTo - This method removes all call edges from this node
282 /// to the specified callee function. This takes more time to execute than
283 /// removeCallEdgeTo, so it should not be used unless necessary.
284 void removeAnyCallEdgeTo(CallGraphNode *Callee);
286 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
287 /// from this node to the specified callee function.
288 void removeOneAbstractEdgeTo(CallGraphNode *Callee);
290 /// replaceCallEdge - This method replaces the edge in the node for the
291 /// specified call site with a new one. Note that this method takes linear
292 /// time, so it should be used sparingly.
293 void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode);
295 /// allReferencesDropped - This is a special function that should only be
296 /// used by the CallGraph class.
297 void allReferencesDropped() {
302 //===----------------------------------------------------------------------===//
303 // GraphTraits specializations for call graphs so that they can be treated as
304 // graphs by the generic graph algorithms.
307 // Provide graph traits for tranversing call graphs using standard graph
309 template <> struct GraphTraits<CallGraphNode*> {
310 typedef CallGraphNode NodeType;
312 typedef CallGraphNode::CallRecord CGNPairTy;
313 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
315 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
317 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
319 static inline ChildIteratorType child_begin(NodeType *N) {
320 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
322 static inline ChildIteratorType child_end (NodeType *N) {
323 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
326 static CallGraphNode *CGNDeref(CGNPairTy P) {
332 template <> struct GraphTraits<const CallGraphNode*> {
333 typedef const CallGraphNode NodeType;
334 typedef NodeType::const_iterator ChildIteratorType;
336 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
337 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
338 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
341 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
342 static NodeType *getEntryNode(CallGraph *CGN) {
343 return CGN->getExternalCallingNode(); // Start at the external node!
345 typedef std::pair<const Function*, CallGraphNode*> PairTy;
346 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
348 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
349 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
350 static nodes_iterator nodes_begin(CallGraph *CG) {
351 return map_iterator(CG->begin(), DerefFun(CGdereference));
353 static nodes_iterator nodes_end (CallGraph *CG) {
354 return map_iterator(CG->end(), DerefFun(CGdereference));
357 static CallGraphNode &CGdereference(PairTy P) {
362 template<> struct GraphTraits<const CallGraph*> :
363 public GraphTraits<const CallGraphNode*> {
364 static NodeType *getEntryNode(const CallGraph *CGN) {
365 return CGN->getExternalCallingNode();
367 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
368 typedef CallGraph::const_iterator nodes_iterator;
369 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
370 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
373 } // End llvm namespace
375 // Make sure that any clients of this file link in CallGraph.cpp
376 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)