llvm-6502/include/llvm/Analysis/CallGraph.h
Chris Lattner 1570cb14d7 Initialize member out of paranoia
git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@13319 91177308-0d34-0410-b5e6-96231b3b80d8
2004-05-02 16:06:40 +00:00

311 lines
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C++

//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
//
// The LLVM Compiler Infrastructure
//
// This file was developed by the LLVM research group and 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 "Support/GraphTraits.h"
#include "Support/STLExtras.h"
#include "llvm/Pass.h"
namespace llvm {
class Function;
class Module;
class CallGraphNode;
//===----------------------------------------------------------------------===//
// CallGraph class definition
//
class CallGraph : public Pass {
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;
public:
//===---------------------------------------------------------------------
// Accessors...
//
typedef FunctionMapTy::iterator iterator;
typedef FunctionMapTy::const_iterator const_iterator;
CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; }
// getRoot - Return the root of the call graph, which is either main, or if
// main cannot be found, the external node.
//
CallGraphNode *getRoot() { return Root; }
const CallGraphNode *getRoot() const { return Root; }
/// 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;
}
//===---------------------------------------------------------------------
// Functions to keep a call graph up to date with a function that has been
// modified
//
void addFunctionToModule(Function *F);
// 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);
Function *removeFunctionFromModule(Function *F) {
return removeFunctionFromModule((*this)[F]);
}
//===---------------------------------------------------------------------
// Pass infrastructure interface glue code...
//
CallGraph() : Root(0), CallsExternalNode(0) {}
~CallGraph() { destroy(); }
// run - Compute the call graph for the specified module.
virtual bool run(Module &M);
// getAnalysisUsage - This obviously provides a call graph
virtual void getAnalysisUsage(AnalysisUsage &AU) const {
AU.setPreservesAll();
}
// releaseMemory - Data structures can be large, so free memory aggressively.
virtual void releaseMemory() {
destroy();
}
/// Print the types found in the module. If the optional Module parameter is
/// passed in, then the types are printed symbolically if possible, using the
/// symbol table from the module.
///
void print(std::ostream &o, const Module *M) const;
// stub - dummy function, just ignore it
static void stub();
private:
//===---------------------------------------------------------------------
// Implementation of CallGraph construction
//
// getNodeFor - Return the node for the specified function or create one if it
// does not already exist.
//
CallGraphNode *getNodeFor(Function *F);
// addToCallGraph - Add a function to the call graph, and link the node to all
// of the functions that it calls.
//
void addToCallGraph(Function *F);
// destroy - Release memory for the call graph
void destroy();
};
//===----------------------------------------------------------------------===//
// CallGraphNode class definition
//
class CallGraphNode {
Function *F;
std::vector<CallGraphNode*> CalledFunctions;
CallGraphNode(const CallGraphNode &); // Do not implement
public:
//===---------------------------------------------------------------------
// Accessor methods...
//
typedef std::vector<CallGraphNode*>::iterator iterator;
typedef std::vector<CallGraphNode*>::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 unsigned size() const { return CalledFunctions.size(); }
// Subscripting operator - Return the i'th called function...
//
CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];}
//===---------------------------------------------------------------------
// Methods to keep a call graph up to date with a function that has been
// modified
//
void removeAllCalledFunctions() {
CalledFunctions.clear();
}
// addCalledFunction add a function to the list of functions called by this
// one
void addCalledFunction(CallGraphNode *M) {
CalledFunctions.push_back(M);
}
void removeCallEdgeTo(CallGraphNode *Callee);
private: // Stuff to construct the node, used by CallGraph
friend class CallGraph;
// CallGraphNode ctor - Create a node for the specified function...
inline CallGraphNode(Function *f) : F(f) {}
};
//===----------------------------------------------------------------------===//
// 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 NodeType::iterator ChildIteratorType;
static NodeType *getEntryNode(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<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 (std::pair<const Function*,
CallGraphNode*> 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(); }
};
// Make sure that any clients of this file link in PostDominators.cpp
static IncludeFile
CALLGRAPH_INCLUDE_FILE((void*)&CallGraph::stub);
} // End llvm namespace
#endif