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//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
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// The LLVM Compiler Infrastructure
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// This file is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//===----------------------------------------------------------------------===//
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// This interface is used to build and manipulate a call graph, which is a very
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// useful tool for interprocedural optimization.
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// Every function in a module is represented as a node in the call graph. The
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// callgraph node keeps track of which functions the are called by the function
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// corresponding to the node.
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// A call graph may contain nodes where the function that they correspond to is
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// null. These 'external' nodes are used to represent control flow that is not
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// represented (or analyzable) in the module. In particular, this analysis
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// builds one external node such that:
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// 1. All functions in the module without internal linkage will have edges
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// from this external node, indicating that they could be called by
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// functions outside of the module.
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// 2. All functions whose address is used for something more than a direct
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// call, for example being stored into a memory location will also have an
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// edge from this external node. Since they may be called by an unknown
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// caller later, they must be tracked as such.
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// There is a second external node added for calls that leave this module.
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// Functions have a call edge to the external node iff:
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// 1. The function is external, reflecting the fact that they could call
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// anything without internal linkage or that has its address taken.
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// 2. The function contains an indirect function call.
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// As an extension in the future, there may be multiple nodes with a null
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// function. These will be used when we can prove (through pointer analysis)
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// that an indirect call site can call only a specific set of functions.
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// Because of these properties, the CallGraph captures a conservative superset
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// of all of the caller-callee relationships, which is useful for
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// The CallGraph class also attempts to figure out what the root of the
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// CallGraph is, which it currently does by looking for a function named 'main'.
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// If no function named 'main' is found, the external node is used as the entry
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// node, reflecting the fact that any function without internal linkage could
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// be called into (which is common for libraries).
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_CALLGRAPH_H
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#define LLVM_ANALYSIS_CALLGRAPH_H
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#include "llvm/Function.h"
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#include "llvm/Pass.h"
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/Support/CallSite.h"
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#include "llvm/Support/ValueHandle.h"
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#include "llvm/System/IncludeFile.h"
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//===----------------------------------------------------------------------===//
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// CallGraph class definition
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Module *Mod; // The module this call graph represents
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typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
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FunctionMapTy FunctionMap; // Map from a function to its node
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static char ID; // Class identification, replacement for typeinfo
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//===---------------------------------------------------------------------
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typedef FunctionMapTy::iterator iterator;
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typedef FunctionMapTy::const_iterator const_iterator;
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/// getModule - Return the module the call graph corresponds to.
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Module &getModule() const { return *Mod; }
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inline iterator begin() { return FunctionMap.begin(); }
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inline iterator end() { return FunctionMap.end(); }
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inline const_iterator begin() const { return FunctionMap.begin(); }
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inline const_iterator end() const { return FunctionMap.end(); }
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// Subscripting operators, return the call graph node for the provided
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inline const CallGraphNode *operator[](const Function *F) const {
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const_iterator I = FunctionMap.find(F);
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assert(I != FunctionMap.end() && "Function not in callgraph!");
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inline CallGraphNode *operator[](const Function *F) {
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const_iterator I = FunctionMap.find(F);
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assert(I != FunctionMap.end() && "Function not in callgraph!");
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/// Returns the CallGraphNode which is used to represent undetermined calls
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/// into the callgraph. Override this if you want behavioral inheritance.
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virtual CallGraphNode* getExternalCallingNode() const { return 0; }
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virtual CallGraphNode* getCallsExternalNode() const { return 0; }
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/// Return the root/main method in the module, or some other root node, such
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/// as the externalcallingnode. Overload these if you behavioral
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virtual CallGraphNode* getRoot() { return 0; }
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virtual const CallGraphNode* getRoot() const { return 0; }
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//===---------------------------------------------------------------------
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// Functions to keep a call graph up to date with a function that has been
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/// removeFunctionFromModule - Unlink the function from this module, returning
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/// it. Because this removes the function from the module, the call graph
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/// node is destroyed. This is only valid if the function does not call any
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/// other functions (ie, there are no edges in it's CGN). The easiest way to
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/// do this is to dropAllReferences before calling this.
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Function *removeFunctionFromModule(CallGraphNode *CGN);
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Function *removeFunctionFromModule(Function *F) {
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return removeFunctionFromModule((*this)[F]);
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/// getOrInsertFunction - This method is identical to calling operator[], but
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/// it will insert a new CallGraphNode for the specified function if one does
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/// not already exist.
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CallGraphNode *getOrInsertFunction(const Function *F);
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//===---------------------------------------------------------------------
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// Pass infrastructure interface glue code.
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virtual ~CallGraph() { destroy(); }
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/// initialize - Call this method before calling other methods,
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/// re/initializes the state of the CallGraph.
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void initialize(Module &M);
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void print(raw_ostream &o, Module *) const;
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// destroy - Release memory for the call graph
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virtual void destroy();
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//===----------------------------------------------------------------------===//
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// CallGraphNode class definition.
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class CallGraphNode {
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AssertingVH<Function> F;
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// CallRecord - This is a pair of the calling instruction (a call or invoke)
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// and the callgraph node being called.
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typedef std::pair<WeakVH, CallGraphNode*> CallRecord;
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std::vector<CallRecord> CalledFunctions;
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/// NumReferences - This is the number of times that this CallGraphNode occurs
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/// in the CalledFunctions array of this or other CallGraphNodes.
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unsigned NumReferences;
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CallGraphNode(const CallGraphNode &); // DO NOT IMPLEMENT
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void operator=(const CallGraphNode &); // DO NOT IMPLEMENT
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void DropRef() { --NumReferences; }
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void AddRef() { ++NumReferences; }
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typedef std::vector<CallRecord> CalledFunctionsVector;
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// CallGraphNode ctor - Create a node for the specified function.
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inline CallGraphNode(Function *f) : F(f), NumReferences(0) {}
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assert(NumReferences == 0 && "Node deleted while references remain");
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//===---------------------------------------------------------------------
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typedef std::vector<CallRecord>::iterator iterator;
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typedef std::vector<CallRecord>::const_iterator const_iterator;
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// getFunction - Return the function that this call graph node represents.
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Function *getFunction() const { return F; }
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inline iterator begin() { return CalledFunctions.begin(); }
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inline iterator end() { return CalledFunctions.end(); }
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inline const_iterator begin() const { return CalledFunctions.begin(); }
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inline const_iterator end() const { return CalledFunctions.end(); }
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inline bool empty() const { return CalledFunctions.empty(); }
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inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
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/// getNumReferences - Return the number of other CallGraphNodes in this
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/// CallGraph that reference this node in their callee list.
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unsigned getNumReferences() const { return NumReferences; }
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// Subscripting operator - Return the i'th called function.
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CallGraphNode *operator[](unsigned i) const {
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assert(i < CalledFunctions.size() && "Invalid index");
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return CalledFunctions[i].second;
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/// dump - Print out this call graph node.
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void print(raw_ostream &OS) const;
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//===---------------------------------------------------------------------
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// Methods to keep a call graph up to date with a function that has been
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/// removeAllCalledFunctions - As the name implies, this removes all edges
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/// from this CallGraphNode to any functions it calls.
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void removeAllCalledFunctions() {
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while (!CalledFunctions.empty()) {
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CalledFunctions.back().second->DropRef();
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CalledFunctions.pop_back();
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/// stealCalledFunctionsFrom - Move all the callee information from N to this
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void stealCalledFunctionsFrom(CallGraphNode *N) {
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assert(CalledFunctions.empty() &&
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"Cannot steal callsite information if I already have some");
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std::swap(CalledFunctions, N->CalledFunctions);
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/// addCalledFunction - Add a function to the list of functions called by this
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void addCalledFunction(CallSite CS, CallGraphNode *M) {
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CalledFunctions.push_back(std::make_pair(CS.getInstruction(), M));
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void removeCallEdge(iterator I) {
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I->second->DropRef();
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*I = CalledFunctions.back();
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CalledFunctions.pop_back();
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/// removeCallEdgeFor - This method removes the edge in the node for the
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/// specified call site. Note that this method takes linear time, so it
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/// should be used sparingly.
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void removeCallEdgeFor(CallSite CS);
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/// removeAnyCallEdgeTo - This method removes all call edges from this node
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/// to the specified callee function. This takes more time to execute than
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/// removeCallEdgeTo, so it should not be used unless necessary.
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void removeAnyCallEdgeTo(CallGraphNode *Callee);
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/// removeOneAbstractEdgeTo - Remove one edge associated with a null callsite
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/// from this node to the specified callee function.
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void removeOneAbstractEdgeTo(CallGraphNode *Callee);
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/// replaceCallEdge - This method replaces the edge in the node for the
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/// specified call site with a new one. Note that this method takes linear
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/// time, so it should be used sparingly.
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void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode);
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/// allReferencesDropped - This is a special function that should only be
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/// used by the CallGraph class.
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void allReferencesDropped() {
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//===----------------------------------------------------------------------===//
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// GraphTraits specializations for call graphs so that they can be treated as
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// graphs by the generic graph algorithms.
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// Provide graph traits for tranversing call graphs using standard graph
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template <> struct GraphTraits<CallGraphNode*> {
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typedef CallGraphNode NodeType;
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typedef CallGraphNode::CallRecord CGNPairTy;
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typedef std::pointer_to_unary_function<CGNPairTy, CallGraphNode*> CGNDerefFun;
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static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
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typedef mapped_iterator<NodeType::iterator, CGNDerefFun> ChildIteratorType;
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static inline ChildIteratorType child_begin(NodeType *N) {
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return map_iterator(N->begin(), CGNDerefFun(CGNDeref));
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static inline ChildIteratorType child_end (NodeType *N) {
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return map_iterator(N->end(), CGNDerefFun(CGNDeref));
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static CallGraphNode *CGNDeref(CGNPairTy P) {
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template <> struct GraphTraits<const CallGraphNode*> {
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typedef const CallGraphNode NodeType;
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typedef NodeType::const_iterator ChildIteratorType;
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static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
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static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
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static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
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template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
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static NodeType *getEntryNode(CallGraph *CGN) {
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return CGN->getExternalCallingNode(); // Start at the external node!
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typedef std::pair<const Function*, CallGraphNode*> PairTy;
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typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
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// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
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typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
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static nodes_iterator nodes_begin(CallGraph *CG) {
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return map_iterator(CG->begin(), DerefFun(CGdereference));
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static nodes_iterator nodes_end (CallGraph *CG) {
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return map_iterator(CG->end(), DerefFun(CGdereference));
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static CallGraphNode &CGdereference(PairTy P) {
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template<> struct GraphTraits<const CallGraph*> :
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public GraphTraits<const CallGraphNode*> {
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static NodeType *getEntryNode(const CallGraph *CGN) {
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return CGN->getExternalCallingNode();
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// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
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typedef CallGraph::const_iterator nodes_iterator;
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static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
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static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
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} // End llvm namespace
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// Make sure that any clients of this file link in CallGraph.cpp
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FORCE_DEFINING_FILE_TO_BE_LINKED(CallGraph)