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