-//===- llvm/Analysis/CallGraph.h - Build a Module's call graph ---*- 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
+// 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.
//
-// This call graph represents a dynamic method invocation as a null method node.
-// A call graph may only have up to one null method node that represents all of
-// the dynamic method invocations.
+// 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 <map>
-#include <vector>
-class Method;
+#include "llvm/ADT/GraphTraits.h"
+#include "llvm/ADT/STLExtras.h"
+#include "llvm/Pass.h"
+
+namespace llvm {
+
+class Function;
class Module;
+class CallGraphNode;
+
+//===----------------------------------------------------------------------===//
+// CallGraph class definition
+//
+class CallGraph {
+protected:
+ Module *Mod; // The module this call graph represents
+
+ typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
+ FunctionMapTy FunctionMap; // Map from a function to its node
+
+public:
+ //===---------------------------------------------------------------------
+ // 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. Override this if you want behavioural inheritance.
+ virtual CallGraphNode* getExternalCallingNode() const { return 0; }
+
+ //Return the root/main method in the module, or some other root node, such
+ // as the externalcallingnode. Overload these if you behavioural
+ // inheritance.
+ virtual CallGraphNode* getRoot() { return 0; }
+ virtual const CallGraphNode* getRoot() const { return 0; }
+
+ //===---------------------------------------------------------------------
+ // 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);
+ Function *removeFunctionFromModule(Function *F) {
+ return removeFunctionFromModule((*this)[F]);
+ }
+
+ /// changeFunction - This method changes the function associated with this
+ /// CallGraphNode, for use by transformations that need to change the
+ /// prototype of a Function (thus they must create a new Function and move the
+ /// old code over).
+ void changeFunction(Function *OldF, Function *NewF);
+
+ //===---------------------------------------------------------------------
+ // Pass infrastructure interface glue code...
+ //
+protected:
+ CallGraph() {}
+
+public:
+ virtual ~CallGraph() { destroy(); }
+
+ /// initialize - Call this method before calling other methods,
+ /// re/initializes the state of the CallGraph.
+ ///
+ void initialize(Module &M);
-namespace cfg {
+ virtual void print(std::ostream &o, const Module *M) const;
+ void dump() const;
+
+ // stub - dummy function, just ignore it
+ static void stub();
+protected:
+
+ // destroy - Release memory for the call graph
+ virtual void destroy();
+};
-class CallGraph;
+//===----------------------------------------------------------------------===//
+// CallGraphNode class definition
+//
class CallGraphNode {
- Method *Meth;
- vector<CallGraphNode*> CalledMethods;
+ Function *F;
+ std::vector<CallGraphNode*> CalledFunctions;
CallGraphNode(const CallGraphNode &); // Do not implement
public:
- typedef vector<CallGraphNode*>::iterator iterator;
- typedef vector<CallGraphNode*>::const_iterator const_iterator;
+ //===---------------------------------------------------------------------
+ // Accessor methods...
+ //
+
+ typedef std::vector<CallGraphNode*>::iterator iterator;
+ typedef std::vector<CallGraphNode*>::const_iterator const_iterator;
- // getMethod - Return the method that this call graph node represents...
- Method *getMethod() const { return Meth; }
+ // getFunction - Return the function that this call graph node represents...
+ Function *getFunction() const { return F; }
- inline iterator begin() { return CalledMethods.begin(); }
- inline iterator end() { return CalledMethods.end(); }
- inline const_iterator begin() const { return CalledMethods.begin(); }
- inline const_iterator end() const { return CalledMethods.end(); }
- inline unsigned size() const { return CalledMethods.size(); }
+ 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(); }
- inline CallGraphNode *operator[](unsigned i) const { return CalledMethods[i];}
+ // Subscripting operator - Return the i'th called function...
+ //
+ CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];}
+ /// dump - Print out this call graph node.
+ ///
+ void dump() const;
+ void print(std::ostream &OS) const;
-private: // Stuff to construct the node, used by CallGraph
- friend class CallGraph;
+ //===---------------------------------------------------------------------
+ // Methods to keep a call graph up to date with a function that has been
+ // modified
+ //
- // CallGraphNode ctor - Create a node for the specified method...
- inline CallGraphNode(Method *M) : Meth(M) {}
-
- // addCalledMethod add a method to the list of methods called by this one
- void addCalledMethod(CallGraphNode *M) {
- CalledMethods.push_back(M);
+ /// removeAllCalledFunctions - As the name implies, this removes all edges
+ /// from this CallGraphNode to any functions it calls.
+ 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);
+ }
+
+ /// removeCallEdgeTo - This method removes a *single* edge to the specified
+ /// callee function. Note that this method takes linear time, so it should be
+ /// used sparingly.
+ void removeCallEdgeTo(CallGraphNode *Callee);
+
+ /// removeAnyCallEdgeTo - This method removes any 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);
+
+ 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...
+//
-class CallGraph {
- Module *Mod;
- typedef map<const Method *, CallGraphNode *> MethodMapTy;
- MethodMapTy MethodMap;
-public:
- CallGraph(Module *TheModule);
+// Provide graph traits for tranversing call graphs using standard graph
+// traversals.
+template <> struct GraphTraits<CallGraphNode*> {
+ typedef CallGraphNode NodeType;
+ typedef NodeType::iterator ChildIteratorType;
- typedef MethodMapTy::iterator iterator;
- typedef MethodMapTy::const_iterator const_iterator;
+ 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(); }
+};
- inline const_iterator begin() const { return MethodMap.begin(); }
- inline const_iterator end() const { return MethodMap.end(); }
+template <> struct GraphTraits<const CallGraphNode*> {
+ typedef const CallGraphNode NodeType;
+ typedef NodeType::const_iterator ChildIteratorType;
- inline const CallGraphNode *operator[](const Method *M) const {
- const_iterator I = MethodMap.find(M);
- assert(I != MethodMap.end() && "Method not in callgraph!");
- return I->second;
+ 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;
-private: // Implementation of CallGraph construction
+ // 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));
+ }
- // getNodeFor - Return the node for the specified method or create one if it
- // does not already exist.
- //
- CallGraphNode *getNodeFor(Method *M);
+ static CallGraphNode &CGdereference (std::pair<const Function*,
+ CallGraphNode*> P) {
+ return *P.second;
+ }
+};
- // addToCallGraph - Add a method to the call graph, and link the node to all
- // of the methods that it calls.
- //
- void addToCallGraph(Method *M);
+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 CallGraph.cpp
+static IncludeFile
+CALLGRAPH_INCLUDE_FILE((void*)&CallGraph::stub);
+
+extern void BasicCallGraphStub();
+static IncludeFile HDR_INCLUDE_CALLGRAPH_CPP((void*)&BasicCallGraphStub);
-} // end namespace cfg
+} // End llvm namespace
#endif
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