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3f0aa3dbf8
llvm-svn: 21408
332 lines
13 KiB
C++
332 lines
13 KiB
C++
//===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
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//
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// The LLVM Compiler Infrastructure
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//
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// This file was developed by the LLVM research group and is distributed under
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// the University of Illinois Open Source License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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//
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// This interface is used to build and manipulate a call graph, which is a very
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// useful tool for interprocedural optimization.
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//
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// Every function in a module is represented as a node in the call graph. The
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// callgraph node keeps track of which functions the are called by the function
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// corresponding to the node.
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//
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// A call graph may contain nodes where the function that they correspond to is
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// null. These 'external' nodes are used to represent control flow that is not
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// represented (or analyzable) in the module. In particular, this analysis
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// builds one external node such that:
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// 1. All functions in the module without internal linkage will have edges
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// from this external node, indicating that they could be called by
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// functions outside of the module.
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// 2. All functions whose address is used for something more than a direct
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// call, for example being stored into a memory location will also have an
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// edge from this external node. Since they may be called by an unknown
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// caller later, they must be tracked as such.
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//
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// There is a second external node added for calls that leave this module.
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// Functions have a call edge to the external node iff:
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// 1. The function is external, reflecting the fact that they could call
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// anything without internal linkage or that has its address taken.
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// 2. The function contains an indirect function call.
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//
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// As an extension in the future, there may be multiple nodes with a null
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// function. These will be used when we can prove (through pointer analysis)
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// that an indirect call site can call only a specific set of functions.
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//
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// Because of these properties, the CallGraph captures a conservative superset
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// of all of the caller-callee relationships, which is useful for
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// transformations.
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//
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// The CallGraph class also attempts to figure out what the root of the
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// CallGraph is, which it currently does by looking for a function named 'main'.
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// If no function named 'main' is found, the external node is used as the entry
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// node, reflecting the fact that any function without internal linkage could
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// be called into (which is common for libraries).
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//
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//===----------------------------------------------------------------------===//
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#ifndef LLVM_ANALYSIS_CALLGRAPH_H
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#define LLVM_ANALYSIS_CALLGRAPH_H
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#include "llvm/ADT/GraphTraits.h"
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#include "llvm/ADT/STLExtras.h"
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#include "llvm/Pass.h"
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namespace llvm {
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class Function;
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class Module;
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class CallGraphNode;
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//===----------------------------------------------------------------------===//
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// CallGraph class definition
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//
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class CallGraph : public ModulePass {
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Module *Mod; // The module this call graph represents
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typedef std::map<const Function *, CallGraphNode *> FunctionMapTy;
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FunctionMapTy FunctionMap; // Map from a function to its node
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// Root is root of the call graph, or the external node if a 'main' function
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// couldn't be found.
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//
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CallGraphNode *Root;
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// ExternalCallingNode - This node has edges to all external functions and
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// those internal functions that have their address taken.
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CallGraphNode *ExternalCallingNode;
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// CallsExternalNode - This node has edges to it from all functions making
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// indirect calls or calling an external function.
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CallGraphNode *CallsExternalNode;
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public:
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//===---------------------------------------------------------------------
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// Accessors...
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//
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typedef FunctionMapTy::iterator iterator;
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typedef FunctionMapTy::const_iterator const_iterator;
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CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
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CallGraphNode *getCallsExternalNode() const { return CallsExternalNode; }
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// getRoot - Return the root of the call graph, which is either main, or if
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// main cannot be found, the external node.
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//
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CallGraphNode *getRoot() { return Root; }
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const CallGraphNode *getRoot() const { return Root; }
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/// getModule - Return the module the call graph corresponds to.
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///
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Module &getModule() const { return *Mod; }
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inline iterator begin() { return FunctionMap.begin(); }
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inline iterator end() { return FunctionMap.end(); }
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inline const_iterator begin() const { return FunctionMap.begin(); }
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inline const_iterator end() const { return FunctionMap.end(); }
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// Subscripting operators, return the call graph node for the provided
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// function
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inline const CallGraphNode *operator[](const Function *F) const {
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const_iterator I = FunctionMap.find(F);
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assert(I != FunctionMap.end() && "Function not in callgraph!");
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return I->second;
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}
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inline CallGraphNode *operator[](const Function *F) {
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const_iterator I = FunctionMap.find(F);
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assert(I != FunctionMap.end() && "Function not in callgraph!");
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return I->second;
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}
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//===---------------------------------------------------------------------
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// Functions to keep a call graph up to date with a function that has been
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// modified.
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//
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/// removeFunctionFromModule - Unlink the function from this module, returning
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/// it. Because this removes the function from the module, the call graph
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/// node is destroyed. This is only valid if the function does not call any
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/// other functions (ie, there are no edges in it's CGN). The easiest way to
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/// do this is to dropAllReferences before calling this.
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///
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Function *removeFunctionFromModule(CallGraphNode *CGN);
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Function *removeFunctionFromModule(Function *F) {
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return removeFunctionFromModule((*this)[F]);
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}
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/// changeFunction - This method changes the function associated with this
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/// CallGraphNode, for use by transformations that need to change the
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/// prototype of a Function (thus they must create a new Function and move the
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/// old code over).
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void changeFunction(Function *OldF, Function *NewF);
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//===---------------------------------------------------------------------
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// Pass infrastructure interface glue code...
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//
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CallGraph() : Root(0), CallsExternalNode(0) {}
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~CallGraph() { destroy(); }
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// runOnModule - Compute the call graph for the specified module.
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virtual bool runOnModule(Module &M);
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// getAnalysisUsage - This obviously provides a call graph
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virtual void getAnalysisUsage(AnalysisUsage &AU) const {
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AU.setPreservesAll();
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}
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// releaseMemory - Data structures can be large, so free memory aggressively.
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virtual void releaseMemory() {
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destroy();
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}
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/// Print the types found in the module. If the optional Module parameter is
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/// passed in, then the types are printed symbolically if possible, using the
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/// symbol table from the module.
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///
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void print(std::ostream &o, const Module *M) const;
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/// dump - Print out this call graph.
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///
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void dump() const;
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// stub - dummy function, just ignore it
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static void stub();
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private:
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//===---------------------------------------------------------------------
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// Implementation of CallGraph construction
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//
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// getNodeFor - Return the node for the specified function or create one if it
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// does not already exist.
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//
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CallGraphNode *getNodeFor(Function *F);
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// addToCallGraph - Add a function to the call graph, and link the node to all
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// of the functions that it calls.
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//
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void addToCallGraph(Function *F);
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// destroy - Release memory for the call graph
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void destroy();
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};
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//===----------------------------------------------------------------------===//
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// CallGraphNode class definition
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//
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class CallGraphNode {
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Function *F;
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std::vector<CallGraphNode*> CalledFunctions;
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CallGraphNode(const CallGraphNode &); // Do not implement
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public:
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//===---------------------------------------------------------------------
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// Accessor methods...
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//
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typedef std::vector<CallGraphNode*>::iterator iterator;
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typedef std::vector<CallGraphNode*>::const_iterator const_iterator;
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// getFunction - Return the function that this call graph node represents...
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Function *getFunction() const { return F; }
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inline iterator begin() { return CalledFunctions.begin(); }
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inline iterator end() { return CalledFunctions.end(); }
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inline const_iterator begin() const { return CalledFunctions.begin(); }
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inline const_iterator end() const { return CalledFunctions.end(); }
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inline unsigned size() const { return CalledFunctions.size(); }
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// Subscripting operator - Return the i'th called function...
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//
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CallGraphNode *operator[](unsigned i) const { return CalledFunctions[i];}
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/// dump - Print out this call graph node.
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///
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void dump() const;
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void print(std::ostream &OS) const;
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//===---------------------------------------------------------------------
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// Methods to keep a call graph up to date with a function that has been
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// modified
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//
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/// removeAllCalledFunctions - As the name implies, this removes all edges
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/// from this CallGraphNode to any functions it calls.
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void removeAllCalledFunctions() {
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CalledFunctions.clear();
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}
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/// addCalledFunction add a function to the list of functions called by this
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/// one.
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void addCalledFunction(CallGraphNode *M) {
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CalledFunctions.push_back(M);
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}
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/// removeCallEdgeTo - This method removes a *single* edge to the specified
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/// callee function. Note that this method takes linear time, so it should be
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/// used sparingly.
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void removeCallEdgeTo(CallGraphNode *Callee);
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/// removeAnyCallEdgeTo - This method removes any call edges from this node to
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/// the specified callee function. This takes more time to execute than
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/// removeCallEdgeTo, so it should not be used unless necessary.
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void removeAnyCallEdgeTo(CallGraphNode *Callee);
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private: // Stuff to construct the node, used by CallGraph
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friend class CallGraph;
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// CallGraphNode ctor - Create a node for the specified function...
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inline CallGraphNode(Function *f) : F(f) {}
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};
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//===----------------------------------------------------------------------===//
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// GraphTraits specializations for call graphs so that they can be treated as
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// graphs by the generic graph algorithms...
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//
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// Provide graph traits for tranversing call graphs using standard graph
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// traversals.
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template <> struct GraphTraits<CallGraphNode*> {
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typedef CallGraphNode NodeType;
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typedef NodeType::iterator ChildIteratorType;
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static NodeType *getEntryNode(CallGraphNode *CGN) { return CGN; }
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static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
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static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
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};
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template <> struct GraphTraits<const CallGraphNode*> {
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typedef const CallGraphNode NodeType;
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typedef NodeType::const_iterator ChildIteratorType;
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static NodeType *getEntryNode(const CallGraphNode *CGN) { return CGN; }
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static inline ChildIteratorType child_begin(NodeType *N) { return N->begin();}
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static inline ChildIteratorType child_end (NodeType *N) { return N->end(); }
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};
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template<> struct GraphTraits<CallGraph*> : public GraphTraits<CallGraphNode*> {
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static NodeType *getEntryNode(CallGraph *CGN) {
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return CGN->getExternalCallingNode(); // Start at the external node!
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}
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typedef std::pair<const Function*, CallGraphNode*> PairTy;
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typedef std::pointer_to_unary_function<PairTy, CallGraphNode&> DerefFun;
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// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
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typedef mapped_iterator<CallGraph::iterator, DerefFun> nodes_iterator;
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static nodes_iterator nodes_begin(CallGraph *CG) {
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return map_iterator(CG->begin(), DerefFun(CGdereference));
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}
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static nodes_iterator nodes_end (CallGraph *CG) {
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return map_iterator(CG->end(), DerefFun(CGdereference));
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}
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static CallGraphNode &CGdereference (std::pair<const Function*,
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CallGraphNode*> P) {
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return *P.second;
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}
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};
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template<> struct GraphTraits<const CallGraph*> :
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public GraphTraits<const CallGraphNode*> {
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static NodeType *getEntryNode(const CallGraph *CGN) {
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return CGN->getExternalCallingNode();
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}
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// nodes_iterator/begin/end - Allow iteration over all nodes in the graph
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typedef CallGraph::const_iterator nodes_iterator;
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static nodes_iterator nodes_begin(const CallGraph *CG) { return CG->begin(); }
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static nodes_iterator nodes_end (const CallGraph *CG) { return CG->end(); }
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};
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// Make sure that any clients of this file link in PostDominators.cpp
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static IncludeFile
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CALLGRAPH_INCLUDE_FILE((void*)&CallGraph::stub);
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} // End llvm namespace
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#endif
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