llvm-6502/include/llvm/Analysis/CallGraph.h
2002-08-21 17:09:45 +00:00

271 lines
9.8 KiB
C++

//===- CallGraph.h - Build a Module's call graph -----------------*- C++ -*--=//
//
// 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 will contain nodes where the function that they correspond to is
// null. This 'external' node is used to represent control flow that is not
// represented (or analyzable) in the module. As such, the external node will
// have edges to functions with the following properties:
// 1. All functions in the module without internal linkage, since they could
// be called by functions outside of the our analysis capability.
// 2. All functions whose address is used for something more than a direct
// call, for example being stored into a memory location. Since they may
// be called by an unknown caller later, they must be tracked as such.
//
// Similarly, 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 is 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 "llvm/Pass.h"
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. ExternalNode is equivalent to (*this)[0].
//
CallGraphNode *Root, *ExternalNode;
public:
//===---------------------------------------------------------------------
// Accessors...
//
typedef FunctionMapTy::iterator iterator;
typedef FunctionMapTy::const_iterator const_iterator;
// getExternalNode - Return the node that points to all functions that are
// accessable from outside of the current program.
//
CallGraphNode *getExternalNode() { return ExternalNode; }
const CallGraphNode *getExternalNode() const { return ExternalNode; }
// 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; }
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 *Meth);
// 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 *Meth) {
return removeFunctionFromModule((*this)[Meth]);
}
//===---------------------------------------------------------------------
// Pass infrastructure interface glue code...
//
CallGraph() : Root(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();
}
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 *Meth;
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 Meth; }
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();
}
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) : Meth(F) {}
// addCalledFunction add a function to the list of functions called by this
// one
void addCalledFunction(CallGraphNode *M) {
CalledFunctions.push_back(M);
}
};
//===----------------------------------------------------------------------===//
// 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->getExternalNode(); // Start at the external node!
}
};
template<> struct GraphTraits<const CallGraph*> :
public GraphTraits<const CallGraphNode*> {
static NodeType *getEntryNode(const CallGraph *CGN) {
return CGN->getExternalNode();
}
};
//===----------------------------------------------------------------------===//
// Printing support for Call Graphs
//
// Stuff for printing out a callgraph...
void WriteToOutput(const CallGraph &, std::ostream &o);
inline std::ostream &operator <<(std::ostream &o, const CallGraph &CG) {
WriteToOutput(CG, o); return o;
}
void WriteToOutput(const CallGraphNode *, std::ostream &o);
inline std::ostream &operator <<(std::ostream &o, const CallGraphNode *CGN) {
WriteToOutput(CGN, o); return o;
}
#endif