llvm-6502/include/llvm/Analysis/CallGraph.h

485 lines
18 KiB
C++

//===- 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.
//
//===----------------------------------------------------------------------===//
/// \file
///
/// This file provides interfaces 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 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/CallSite.h"
#include "llvm/IR/Function.h"
#include "llvm/IR/ValueHandle.h"
#include "llvm/Pass.h"
#include <map>
namespace llvm {
class Function;
class Module;
class CallGraphNode;
/// \brief The basic data container for the call graph of a \c Module of IR.
///
/// This class exposes both the interface to the call graph for a module of IR.
///
/// The core call graph itself can also be updated to reflect changes to the IR.
class CallGraph {
Module &M;
typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
/// \brief A map from \c Function* to \c CallGraphNode*.
FunctionMapTy FunctionMap;
/// \brief Root is root of the call graph, or the external node if a 'main'
/// function couldn't be found.
CallGraphNode *Root;
/// \brief This node has edges to all external functions and those internal
/// functions that have their address taken.
CallGraphNode *ExternalCallingNode;
/// \brief This node has edges to it from all functions making indirect calls
/// or calling an external function.
CallGraphNode *CallsExternalNode;
/// \brief 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);
/// \brief Add a function to the call graph, and link the node to all of the
/// functions that it calls.
void addToCallGraph(Function *F);
public:
CallGraph(Module &M);
~CallGraph();
void print(raw_ostream &OS) const;
void dump() const;
typedef FunctionMapTy::iterator iterator;
typedef FunctionMapTy::const_iterator const_iterator;
/// \brief Returns the module the call graph corresponds to.
Module &getModule() const { return M; }
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(); }
/// \brief Returns 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;
}
/// \brief Returns the call graph node for the provided function.
inline CallGraphNode *operator[](const Function *F) {
const_iterator I = FunctionMap.find(F);
assert(I != FunctionMap.end() && "Function not in callgraph!");
return I->second;
}
/// \brief Returns the \c CallGraphNode which is used to represent
/// undetermined calls into the callgraph.
CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; }
//===---------------------------------------------------------------------
// Functions to keep a call graph up to date with a function that has been
// modified.
//
/// \brief 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);
/// \brief Similar to operator[], but this will insert a new CallGraphNode for
/// \c F if one does not already exist.
CallGraphNode *getOrInsertFunction(const Function *F);
};
/// \brief A node in the call graph for a module.
///
/// Typically represents a function in the call graph. There are also special
/// "null" nodes used to represent theoretical entries in the call graph.
class CallGraphNode {
public:
/// \brief A pair of the calling instruction (a call or invoke)
/// and the call graph node being called.
typedef std::pair<WeakVH, CallGraphNode *> CallRecord;
public:
typedef std::vector<CallRecord> CalledFunctionsVector;
/// \brief Creates a node for the specified function.
inline CallGraphNode(Function *F) : F(F), NumReferences(0) {}
~CallGraphNode() {
assert(NumReferences == 0 && "Node deleted while references remain");
}
typedef std::vector<CallRecord>::iterator iterator;
typedef std::vector<CallRecord>::const_iterator const_iterator;
/// \brief Returns 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(); }
/// \brief Returns the number of other CallGraphNodes in this CallGraph that
/// reference this node in their callee list.
unsigned getNumReferences() const { return NumReferences; }
/// \brief Returns the i'th called function.
CallGraphNode *operator[](unsigned i) const {
assert(i < CalledFunctions.size() && "Invalid index");
return CalledFunctions[i].second;
}
/// \brief 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
//
/// \brief Removes all edges from this CallGraphNode to any functions it
/// calls.
void removeAllCalledFunctions() {
while (!CalledFunctions.empty()) {
CalledFunctions.back().second->DropRef();
CalledFunctions.pop_back();
}
}
/// \brief Moves 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);
}
/// \brief Adds 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();
}
/// \brief 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);
/// \brief 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);
/// \brief Removes one edge associated with a null callsite from this node to
/// the specified callee function.
void removeOneAbstractEdgeTo(CallGraphNode *Callee);
/// \brief 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);
private:
friend class CallGraph;
AssertingVH<Function> F;
std::vector<CallRecord> CalledFunctions;
/// \brief The number of times that this CallGraphNode occurs in the
/// CalledFunctions array of this or other CallGraphNodes.
unsigned NumReferences;
CallGraphNode(const CallGraphNode &) = delete;
void operator=(const CallGraphNode &) = delete;
void DropRef() { --NumReferences; }
void AddRef() { ++NumReferences; }
/// \brief A special function that should only be used by the CallGraph class.
void allReferencesDropped() { NumReferences = 0; }
};
/// \brief An analysis pass to compute the \c CallGraph for a \c Module.
///
/// This class implements the concept of an analysis pass used by the \c
/// ModuleAnalysisManager to run an analysis over a module and cache the
/// resulting data.
class CallGraphAnalysis {
public:
/// \brief A formulaic typedef to inform clients of the result type.
typedef CallGraph Result;
static void *ID() { return (void *)&PassID; }
/// \brief Compute the \c CallGraph for the module \c M.
///
/// The real work here is done in the \c CallGraph constructor.
CallGraph run(Module *M) { return CallGraph(*M); }
private:
static char PassID;
};
/// \brief The \c ModulePass which wraps up a \c CallGraph and the logic to
/// build it.
///
/// This class exposes both the interface to the call graph container and the
/// module pass which runs over a module of IR and produces the call graph. The
/// call graph interface is entirelly a wrapper around a \c CallGraph object
/// which is stored internally for each module.
class CallGraphWrapperPass : public ModulePass {
std::unique_ptr<CallGraph> G;
public:
static char ID; // Class identification, replacement for typeinfo
CallGraphWrapperPass();
virtual ~CallGraphWrapperPass();
/// \brief The internal \c CallGraph around which the rest of this interface
/// is wrapped.
const CallGraph &getCallGraph() const { return *G; }
CallGraph &getCallGraph() { return *G; }
typedef CallGraph::iterator iterator;
typedef CallGraph::const_iterator const_iterator;
/// \brief Returns the module the call graph corresponds to.
Module &getModule() const { return G->getModule(); }
inline iterator begin() { return G->begin(); }
inline iterator end() { return G->end(); }
inline const_iterator begin() const { return G->begin(); }
inline const_iterator end() const { return G->end(); }
/// \brief Returns the call graph node for the provided function.
inline const CallGraphNode *operator[](const Function *F) const {
return (*G)[F];
}
/// \brief Returns the call graph node for the provided function.
inline CallGraphNode *operator[](const Function *F) { return (*G)[F]; }
/// \brief Returns the \c CallGraphNode which is used to represent
/// undetermined calls into the callgraph.
CallGraphNode *getExternalCallingNode() const {
return G->getExternalCallingNode();
}
CallGraphNode *getCallsExternalNode() const {
return G->getCallsExternalNode();
}
//===---------------------------------------------------------------------
// Functions to keep a call graph up to date with a function that has been
// modified.
//
/// \brief 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) {
return G->removeFunctionFromModule(CGN);
}
/// \brief Similar to operator[], but this will insert a new CallGraphNode for
/// \c F if one does not already exist.
CallGraphNode *getOrInsertFunction(const Function *F) {
return G->getOrInsertFunction(F);
}
//===---------------------------------------------------------------------
// Implementation of the ModulePass interface needed here.
//
void getAnalysisUsage(AnalysisUsage &AU) const override;
bool runOnModule(Module &M) override;
void releaseMemory() override;
void print(raw_ostream &o, const Module *) const override;
void dump() const;
};
//===----------------------------------------------------------------------===//
// 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 CallGraphNode::CallRecord CGNPairTy;
typedef std::pointer_to_unary_function<CGNPairTy, const CallGraphNode *>
CGNDerefFun;
static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
typedef mapped_iterator<NodeType::const_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 const CallGraphNode *CGNDeref(CGNPairTy P) { return P.second; }
};
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(); // Start at the external node!
}
typedef std::pair<const Function *, const CallGraphNode *> PairTy;
typedef std::pointer_to_unary_function<PairTy, const CallGraphNode &>
DerefFun;
// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
typedef mapped_iterator<CallGraph::const_iterator, DerefFun> nodes_iterator;
static nodes_iterator nodes_begin(const CallGraph *CG) {
return map_iterator(CG->begin(), DerefFun(CGdereference));
}
static nodes_iterator nodes_end(const CallGraph *CG) {
return map_iterator(CG->end(), DerefFun(CGdereference));
}
static const CallGraphNode &CGdereference(PairTy P) { return *P.second; }
};
} // End llvm namespace
#endif