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
72 class CallGraph : public ModulePass {
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
78 // Root is root of the call graph, or the external node if a 'main' function
83 // ExternalCallingNode - This node has edges to all external functions and
84 // those internal functions that have their address taken.
85 CallGraphNode *ExternalCallingNode;
87 // CallsExternalNode - This node has edges to it from all functions making
88 // indirect calls or calling an external function.
89 CallGraphNode *CallsExternalNode;
91 /// Replace the function represented by this node by another.
92 /// This does not rescan the body of the function, so it is suitable when
93 /// splicing the body of one function to another while also updating all
94 /// callers from the old function to the new.
96 void spliceFunction(const Function *From, const Function *To);
98 // Add a function to the call graph, and link the node to all of the functions
100 void addToCallGraph(Function *F);
103 static char ID; // Class identification, replacement for typeinfo
104 //===---------------------------------------------------------------------
107 typedef FunctionMapTy::iterator iterator;
108 typedef FunctionMapTy::const_iterator const_iterator;
110 /// getModule - Return the module the call graph corresponds to.
112 Module &getModule() const { return *Mod; }
114 inline iterator begin() { return FunctionMap.begin(); }
115 inline iterator end() { return FunctionMap.end(); }
116 inline const_iterator begin() const { return FunctionMap.begin(); }
117 inline const_iterator end() const { return FunctionMap.end(); }
119 // Subscripting operators, return the call graph node for the provided
121 inline const CallGraphNode *operator[](const Function *F) const {
122 const_iterator I = FunctionMap.find(F);
123 assert(I != FunctionMap.end() && "Function not in callgraph!");
126 inline CallGraphNode *operator[](const Function *F) {
127 const_iterator I = FunctionMap.find(F);
128 assert(I != FunctionMap.end() && "Function not in callgraph!");
132 /// Returns the CallGraphNode which is used to represent undetermined calls
133 /// into the callgraph.
134 CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
135 CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; }
137 /// Return the root/main method in the module, or some other root node, such
138 /// as the externalcallingnode.
139 CallGraphNode *getRoot() { return Root; }
140 const CallGraphNode *getRoot() const { return Root; }
142 //===---------------------------------------------------------------------
143 // Functions to keep a call graph up to date with a function that has been
147 /// removeFunctionFromModule - Unlink the function from this module, returning
148 /// it. Because this removes the function from the module, the call graph
149 /// node is destroyed. This is only valid if the function does not call any
150 /// other functions (ie, there are no edges in it's CGN). The easiest way to
151 /// do this is to dropAllReferences before calling this.
153 Function *removeFunctionFromModule(CallGraphNode *CGN);
155 /// getOrInsertFunction - This method is identical to calling operator[], but
156 /// it will insert a new CallGraphNode for the specified function if one does
157 /// not already exist.
158 CallGraphNode *getOrInsertFunction(const Function *F);
161 virtual ~CallGraph() { releaseMemory(); }
162 virtual void getAnalysisUsage(AnalysisUsage &AU) const;
163 virtual bool runOnModule(Module &M);
164 virtual void releaseMemory();
166 void print(raw_ostream &o, const Module *) const;
170 //===----------------------------------------------------------------------===//
171 // CallGraphNode class definition.
173 class CallGraphNode {
174 friend class CallGraph;
176 AssertingVH<Function> F;
178 // CallRecord - This is a pair of the calling instruction (a call or invoke)
179 // and the callgraph node being called.
181 typedef std::pair<WeakVH, CallGraphNode*> CallRecord;
183 std::vector<CallRecord> CalledFunctions;
185 /// NumReferences - This is the number of times that this CallGraphNode occurs
186 /// in the CalledFunctions array of this or other CallGraphNodes.
187 unsigned NumReferences;
189 CallGraphNode(const CallGraphNode &) LLVM_DELETED_FUNCTION;
190 void operator=(const CallGraphNode &) LLVM_DELETED_FUNCTION;
192 void DropRef() { --NumReferences; }
193 void AddRef() { ++NumReferences; }
195 typedef std::vector<CallRecord> CalledFunctionsVector;
198 // CallGraphNode ctor - Create a node for the specified function.
199 inline CallGraphNode(Function *f) : F(f), NumReferences(0) {}
201 assert(NumReferences == 0 && "Node deleted while references remain");
204 //===---------------------------------------------------------------------
208 typedef std::vector<CallRecord>::iterator iterator;
209 typedef std::vector<CallRecord>::const_iterator const_iterator;
211 // getFunction - Return the function that this call graph node represents.
212 Function *getFunction() const { return F; }
214 inline iterator begin() { return CalledFunctions.begin(); }
215 inline iterator end() { return CalledFunctions.end(); }
216 inline const_iterator begin() const { return CalledFunctions.begin(); }
217 inline const_iterator end() const { return CalledFunctions.end(); }
218 inline bool empty() const { return CalledFunctions.empty(); }
219 inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
221 /// getNumReferences - Return the number of other CallGraphNodes in this
222 /// CallGraph that reference this node in their callee list.
223 unsigned getNumReferences() const { return NumReferences; }
225 // Subscripting operator - Return the i'th called function.
227 CallGraphNode *operator[](unsigned i) const {
228 assert(i < CalledFunctions.size() && "Invalid index");
229 return CalledFunctions[i].second;
232 /// dump - Print out this call graph node.
235 void print(raw_ostream &OS) const;
237 //===---------------------------------------------------------------------
238 // Methods to keep a call graph up to date with a function that has been
242 /// removeAllCalledFunctions - As the name implies, this removes all edges
243 /// from this CallGraphNode to any functions it calls.
244 void removeAllCalledFunctions() {
245 while (!CalledFunctions.empty()) {
246 CalledFunctions.back().second->DropRef();
247 CalledFunctions.pop_back();
251 /// stealCalledFunctionsFrom - Move all the callee information from N to this
253 void stealCalledFunctionsFrom(CallGraphNode *N) {
254 assert(CalledFunctions.empty() &&
255 "Cannot steal callsite information if I already have some");
256 std::swap(CalledFunctions, N->CalledFunctions);
260 /// addCalledFunction - Add a function to the list of functions called by this
262 void addCalledFunction(CallSite CS, CallGraphNode *M) {
263 assert(!CS.getInstruction() ||
264 !CS.getCalledFunction() ||
265 !CS.getCalledFunction()->isIntrinsic());
266 CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M));
270 void removeCallEdge(iterator I) {
271 I->second->DropRef();
272 *I = CalledFunctions.back();
273 CalledFunctions.pop_back();
277 /// removeCallEdgeFor - This method removes the edge in the node for the
278 /// specified call site. Note that this method takes linear time, so it
279 /// should be used sparingly.
280 void removeCallEdgeFor(CallSite CS);
282 /// removeAnyCallEdgeTo - This method removes all call edges from this node
283 /// to the specified callee function. This takes more time to execute than
284 /// removeCallEdgeTo, so it should not be used unless necessary.
285 void removeAnyCallEdgeTo(CallGraphNode *Callee);
287 /// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
288 /// from this node to the specified callee function.
289 void removeOneAbstractEdgeTo(CallGraphNode *Callee);
291 /// replaceCallEdge - This method replaces the edge in the node for the
292 /// specified call site with a new one. Note that this method takes linear
293 /// time, so it should be used sparingly.
294 void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode);
296 /// allReferencesDropped - This is a special function that should only be
297 /// used by the CallGraph class.
298 void allReferencesDropped() {
303 //===----------------------------------------------------------------------===//
304 // GraphTraits specializations for call graphs so that they can be treated as
305 // graphs by the generic graph algorithms.
308 // Provide graph traits for tranversing call graphs using standard graph
310 template <> struct GraphTraits<CallGraphNode*> {
311 typedef CallGraphNode NodeType;
313 typedef CallGraphNode::CallRecord CGNPairTy;
314 typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
316 static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
318 typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
320 static inline ChildIteratorType child_begin(NodeType *N) {
321 return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
323 static inline ChildIteratorType child_end (NodeType *N) {
324 return map_iterator(N->end(), CGNDerefFun(CGNDeref));
327 static CallGraphNode *CGNDeref(CGNPairTy P) {
333 template <> struct GraphTraits<const CallGraphNode*> {
334 typedef const CallGraphNode NodeType;
335 typedef NodeType::const_iterator ChildIteratorType;
337 static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
338 static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
339 static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
342 template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
343 static NodeType *getEntryNode(CallGraph *CGN) {
344 return CGN->getExternalCallingNode(); // Start at the external node!
346 typedef std::pair<const Function*, CallGraphNode*> PairTy;
347 typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
349 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
350 typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
351 static nodes_iterator nodes_begin(CallGraph *CG) {
352 return map_iterator(CG->begin(), DerefFun(CGdereference));
354 static nodes_iterator nodes_end (CallGraph *CG) {
355 return map_iterator(CG->end(), DerefFun(CGdereference));
358 static CallGraphNode &CGdereference(PairTy P) {
363 template<> struct GraphTraits<const CallGraph*> :
364 public GraphTraits<const CallGraphNode*> {
365 static NodeType *getEntryNode(const CallGraph *CGN) {
366 return CGN->getExternalCallingNode();
368 // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
369 typedef CallGraph::const_iterator nodes_iterator;
370 static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
371 static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
374 } // End llvm namespace
376 // Make sure that any clients of this file link in CallGraph.cpp
377 FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)