Coverage Report

Created: 2018-07-19 03:59

/Users/buildslave/jenkins/workspace/clang-stage2-coverage-R/llvm/include/llvm/Analysis/CallGraph.h
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//===- 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 is distributed under the University of Illinois Open Source
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// License. See LICENSE.TXT for details.
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//
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//===----------------------------------------------------------------------===//
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/// \file
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///
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/// This file provides interfaces used to build and manipulate a call graph,
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/// which is a very 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 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
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/// is null.  These 'external' nodes are used to represent control flow that is
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/// not represented (or analyzable) in the module.  In particular, this
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/// analysis 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
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///      an edge from this external node.  Since they may be called by an
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///      unknown 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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//===----------------------------------------------------------------------===//
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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/IR/CallSite.h"
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#include "llvm/IR/Function.h"
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#include "llvm/IR/Intrinsics.h"
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#include "llvm/IR/PassManager.h"
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#include "llvm/IR/ValueHandle.h"
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#include "llvm/Pass.h"
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#include <cassert>
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#include <map>
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#include <memory>
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#include <utility>
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#include <vector>
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namespace llvm {
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class CallGraphNode;
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class Module;
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class raw_ostream;
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/// The basic data container for the call graph of a \c Module of IR.
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///
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/// This class exposes both the interface to the call graph for a module of IR.
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///
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/// The core call graph itself can also be updated to reflect changes to the IR.
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class CallGraph {
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  Module &M;
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  using FunctionMapTy =
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      std::map<const Function *, std::unique_ptr<CallGraphNode>>;
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  /// A map from \c Function* to \c CallGraphNode*.
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  FunctionMapTy FunctionMap;
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  /// This node has edges to all external functions and those internal
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  /// functions that have their address taken.
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  CallGraphNode *ExternalCallingNode;
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  /// This node has edges to it from all functions making indirect calls
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  /// or calling an external function.
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  std::unique_ptr<CallGraphNode> CallsExternalNode;
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  /// Replace the function represented by this node by another.
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  ///
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  /// This does not rescan the body of the function, so it is suitable when
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  /// splicing the body of one function to another while also updating all
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  /// callers from the old function to the new.
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  void spliceFunction(const Function *From, const Function *To);
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  /// Add a function to the call graph, and link the node to all of the
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  /// functions that it calls.
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  void addToCallGraph(Function *F);
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public:
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  explicit CallGraph(Module &M);
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  CallGraph(CallGraph &&Arg);
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  ~CallGraph();
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  void print(raw_ostream &OS) const;
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  void dump() const;
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  using iterator = FunctionMapTy::iterator;
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  using const_iterator = FunctionMapTy::const_iterator;
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  /// Returns the module the call graph corresponds to.
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5.80M
  Module &getModule() const { return M; }
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23.4k
  inline iterator begin() { return FunctionMap.begin(); }
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23.4k
  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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  /// Returns the call graph node for the provided function.
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0
  inline const CallGraphNode *operator[](const Function *F) const {
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0
    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.get();
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0
  }
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  /// Returns the call graph node for the provided function.
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1.12M
  inline CallGraphNode *operator[](const Function *F) {
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1.12M
    const_iterator I = FunctionMap.find(F);
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1.12M
    assert(I != FunctionMap.end() && "Function not in callgraph!");
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1.12M
    return I->second.get();
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1.12M
  }
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  /// Returns the \c CallGraphNode which is used to represent
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  /// undetermined calls into the callgraph.
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225k
  CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
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5.47k
  CallGraphNode *getCallsExternalNode() const {
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5.47k
    return CallsExternalNode.get();
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5.47k
  }
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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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  /// Unlink the function from this module, returning it.
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  ///
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  /// Because this removes the function from the module, the call graph node is
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  /// destroyed.  This is only valid if the function does not call any other
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  /// functions (ie, there are no edges in it's CGN).  The easiest way to do
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  /// this is to dropAllReferences before calling this.
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  Function *removeFunctionFromModule(CallGraphNode *CGN);
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  /// Similar to operator[], but this will insert a new CallGraphNode for
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  /// \c F if one does not already exist.
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  CallGraphNode *getOrInsertFunction(const Function *F);
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};
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/// A node in the call graph for a module.
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///
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/// Typically represents a function in the call graph. There are also special
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/// "null" nodes used to represent theoretical entries in the call graph.
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class CallGraphNode {
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public:
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  /// A pair of the calling instruction (a call or invoke)
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  /// and the call graph node being called.
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  using CallRecord = std::pair<WeakTrackingVH, CallGraphNode *>;
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public:
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  using CalledFunctionsVector = std::vector<CallRecord>;
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  /// Creates a node for the specified function.
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1.74M
  inline CallGraphNode(Function *F) : F(F) {}
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  CallGraphNode(const CallGraphNode &) = delete;
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  CallGraphNode &operator=(const CallGraphNode &) = delete;
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1.74M
  ~CallGraphNode() {
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1.74M
    assert(NumReferences == 0 && "Node deleted while references remain");
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1.74M
  }
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  using iterator = std::vector<CallRecord>::iterator;
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  using const_iterator = std::vector<CallRecord>::const_iterator;
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  /// Returns the function that this call graph node represents.
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12.2M
  Function *getFunction() const { return F; }
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4.27M
  inline iterator begin() { return CalledFunctions.begin(); }
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17.9M
  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 bool empty() const { return CalledFunctions.empty(); }
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  inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
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  /// Returns the number of other CallGraphNodes in this CallGraph that
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  /// reference this node in their callee list.
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39.7k
  unsigned getNumReferences() const { return NumReferences; }
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  /// Returns the i'th called function.
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  CallGraphNode *operator[](unsigned i) const {
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    assert(i < CalledFunctions.size() && "Invalid index");
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    return CalledFunctions[i].second;
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  }
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  /// Print out this call graph node.
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  void dump() const;
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  void print(raw_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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  /// Removes all edges from this CallGraphNode to any functions it
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  /// calls.
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171k
  void removeAllCalledFunctions() {
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304k
    while (!CalledFunctions.empty()) {
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133k
      CalledFunctions.back().second->DropRef();
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      CalledFunctions.pop_back();
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    }
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  }
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  /// Moves all the callee information from N to this node.
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1.71k
  void stealCalledFunctionsFrom(CallGraphNode *N) {
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1.71k
    assert(CalledFunctions.empty() &&
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1.71k
           "Cannot steal callsite information if I already have some");
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1.71k
    std::swap(CalledFunctions, N->CalledFunctions);
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1.71k
  }
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  /// Adds a function to the list of functions called by this one.
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7.15M
  void addCalledFunction(CallSite CS, CallGraphNode *M) {
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7.15M
    assert(!CS.getInstruction() || !CS.getCalledFunction() ||
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7.15M
           !CS.getCalledFunction()->isIntrinsic() ||
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7.15M
           !Intrinsic::isLeaf(CS.getCalledFunction()->getIntrinsicID()));
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7.15M
    CalledFunctions.emplace_back(CS.getInstruction(), M);
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7.15M
    M->AddRef();
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7.15M
  }
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36.0k
  void removeCallEdge(iterator I) {
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36.0k
    I->second->DropRef();
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36.0k
    *I = CalledFunctions.back();
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36.0k
    CalledFunctions.pop_back();
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  }
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  /// Removes the edge in the node for the specified call site.
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  ///
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  /// Note that this method takes linear time, so it should be used sparingly.
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  void removeCallEdgeFor(CallSite CS);
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  /// Removes all call edges from this node to the specified callee
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  /// function.
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  ///
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  /// This takes more time to execute than removeCallEdgeTo, so it should not
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  /// be used unless necessary.
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  void removeAnyCallEdgeTo(CallGraphNode *Callee);
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  /// Removes one edge associated with a null callsite from this node to
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  /// the specified callee function.
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  void removeOneAbstractEdgeTo(CallGraphNode *Callee);
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  /// Replaces the edge in the node for the specified call site with a
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  /// new one.
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  ///
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  /// Note that this method takes linear time, so it should be used sparingly.
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  void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode);
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private:
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  friend class CallGraph;
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  Function *F;
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  std::vector<CallRecord> CalledFunctions;
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  /// The number of times that this CallGraphNode occurs in the
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  /// CalledFunctions array of this or other CallGraphNodes.
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  unsigned NumReferences = 0;
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776k
  void DropRef() { --NumReferences; }
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7.17M
  void AddRef() { ++NumReferences; }
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  /// A special function that should only be used by the CallGraph class.
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52.2k
  void allReferencesDropped() { NumReferences = 0; }
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};
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/// An analysis pass to compute the \c CallGraph for a \c Module.
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///
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/// This class implements the concept of an analysis pass used by the \c
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/// ModuleAnalysisManager to run an analysis over a module and cache the
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/// resulting data.
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class CallGraphAnalysis : public AnalysisInfoMixin<CallGraphAnalysis> {
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  friend AnalysisInfoMixin<CallGraphAnalysis>;
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  static AnalysisKey Key;
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public:
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  /// A formulaic type to inform clients of the result type.
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  using Result = CallGraph;
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  /// Compute the \c CallGraph for the module \c M.
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  ///
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  /// The real work here is done in the \c CallGraph constructor.
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  CallGraph run(Module &M, ModuleAnalysisManager &) { return CallGraph(M); }
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};
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/// Printer pass for the \c CallGraphAnalysis results.
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class CallGraphPrinterPass : public PassInfoMixin<CallGraphPrinterPass> {
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  raw_ostream &OS;
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public:
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  explicit CallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}
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  PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
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};
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/// The \c ModulePass which wraps up a \c CallGraph and the logic to
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/// build it.
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///
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/// This class exposes both the interface to the call graph container and the
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/// module pass which runs over a module of IR and produces the call graph. The
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/// call graph interface is entirelly a wrapper around a \c CallGraph object
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/// which is stored internally for each module.
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class CallGraphWrapperPass : public ModulePass {
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  std::unique_ptr<CallGraph> G;
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public:
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  static char ID; // Class identification, replacement for typeinfo
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  CallGraphWrapperPass();
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  ~CallGraphWrapperPass() override;
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  /// The internal \c CallGraph around which the rest of this interface
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  /// is wrapped.
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0
  const CallGraph &getCallGraph() const { return *G; }
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2.05M
  CallGraph &getCallGraph() { return *G; }
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  using iterator = CallGraph::iterator;
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  using const_iterator = CallGraph::const_iterator;
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  /// Returns the module the call graph corresponds to.
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0
  Module &getModule() const { return G->getModule(); }
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  inline iterator begin() { return G->begin(); }
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  inline iterator end() { return G->end(); }
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  inline const_iterator begin() const { return G->begin(); }
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  inline const_iterator end() const { return G->end(); }
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  /// Returns the call graph node for the provided function.
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0
  inline const CallGraphNode *operator[](const Function *F) const {
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0
    return (*G)[F];
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0
  }
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  /// Returns the call graph node for the provided function.
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0
  inline CallGraphNode *operator[](const Function *F) { return (*G)[F]; }
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  /// Returns the \c CallGraphNode which is used to represent
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  /// undetermined calls into the callgraph.
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0
  CallGraphNode *getExternalCallingNode() const {
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0
    return G->getExternalCallingNode();
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0
  }
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0
  CallGraphNode *getCallsExternalNode() const {
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0
    return G->getCallsExternalNode();
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0
  }
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  //===---------------------------------------------------------------------
368
  // Functions to keep a call graph up to date with a function that has been
369
  // modified.
370
  //
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372
  /// Unlink the function from this module, returning it.
373
  ///
374
  /// Because this removes the function from the module, the call graph node is
375
  /// destroyed.  This is only valid if the function does not call any other
376
  /// functions (ie, there are no edges in it's CGN).  The easiest way to do
377
  /// this is to dropAllReferences before calling this.
378
0
  Function *removeFunctionFromModule(CallGraphNode *CGN) {
379
0
    return G->removeFunctionFromModule(CGN);
380
0
  }
381
382
  /// Similar to operator[], but this will insert a new CallGraphNode for
383
  /// \c F if one does not already exist.
384
0
  CallGraphNode *getOrInsertFunction(const Function *F) {
385
0
    return G->getOrInsertFunction(F);
386
0
  }
387
388
  //===---------------------------------------------------------------------
389
  // Implementation of the ModulePass interface needed here.
390
  //
391
392
  void getAnalysisUsage(AnalysisUsage &AU) const override;
393
  bool runOnModule(Module &M) override;
394
  void releaseMemory() override;
395
396
  void print(raw_ostream &o, const Module *) const override;
397
  void dump() const;
398
};
399
400
//===----------------------------------------------------------------------===//
401
// GraphTraits specializations for call graphs so that they can be treated as
402
// graphs by the generic graph algorithms.
403
//
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405
// Provide graph traits for tranversing call graphs using standard graph
406
// traversals.
407
template <> struct GraphTraits<CallGraphNode *> {
408
  using NodeRef = CallGraphNode *;
409
  using CGNPairTy = CallGraphNode::CallRecord;
410
411
  static NodeRef getEntryNode(CallGraphNode *CGN) { return CGN; }
412
13.6M
  static CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
413
414
  using ChildIteratorType =
415
      mapped_iterator<CallGraphNode::iterator, decltype(&CGNGetValue)>;
416
417
3.39M
  static ChildIteratorType child_begin(NodeRef N) {
418
3.39M
    return ChildIteratorType(N->begin(), &CGNGetValue);
419
3.39M
  }
420
421
17.0M
  static ChildIteratorType child_end(NodeRef N) {
422
17.0M
    return ChildIteratorType(N->end(), &CGNGetValue);
423
17.0M
  }
424
};
425
426
template <> struct GraphTraits<const CallGraphNode *> {
427
  using NodeRef = const CallGraphNode *;
428
  using CGNPairTy = CallGraphNode::CallRecord;
429
  using EdgeRef = const CallGraphNode::CallRecord &;
430
431
  static NodeRef getEntryNode(const CallGraphNode *CGN) { return CGN; }
432
22
  static const CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
433
434
  using ChildIteratorType =
435
      mapped_iterator<CallGraphNode::const_iterator, decltype(&CGNGetValue)>;
436
  using ChildEdgeIteratorType = CallGraphNode::const_iterator;
437
438
20
  static ChildIteratorType child_begin(NodeRef N) {
439
20
    return ChildIteratorType(N->begin(), &CGNGetValue);
440
20
  }
441
442
42
  static ChildIteratorType child_end(NodeRef N) {
443
42
    return ChildIteratorType(N->end(), &CGNGetValue);
444
42
  }
445
446
19
  static ChildEdgeIteratorType child_edge_begin(NodeRef N) {
447
19
    return N->begin();
448
19
  }
449
19
  static ChildEdgeIteratorType child_edge_end(NodeRef N) { return N->end(); }
450
451
29
  static NodeRef edge_dest(EdgeRef E) { return E.second; }
452
};
453
454
template <>
455
struct GraphTraits<CallGraph *> : public GraphTraits<CallGraphNode *> {
456
  using PairTy =
457
      std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
458
459
92.0k
  static NodeRef getEntryNode(CallGraph *CGN) {
460
92.0k
    return CGN->getExternalCallingNode(); // Start at the external node!
461
92.0k
  }
462
463
0
  static CallGraphNode *CGGetValuePtr(const PairTy &P) {
464
0
    return P.second.get();
465
0
  }
466
467
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
468
  using nodes_iterator =
469
      mapped_iterator<CallGraph::iterator, decltype(&CGGetValuePtr)>;
470
471
1
  static nodes_iterator nodes_begin(CallGraph *CG) {
472
1
    return nodes_iterator(CG->begin(), &CGGetValuePtr);
473
1
  }
474
475
1
  static nodes_iterator nodes_end(CallGraph *CG) {
476
1
    return nodes_iterator(CG->end(), &CGGetValuePtr);
477
1
  }
478
};
479
480
template <>
481
struct GraphTraits<const CallGraph *> : public GraphTraits<
482
                                            const CallGraphNode *> {
483
  using PairTy =
484
      std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
485
486
4
  static NodeRef getEntryNode(const CallGraph *CGN) {
487
4
    return CGN->getExternalCallingNode(); // Start at the external node!
488
4
  }
489
490
  static const CallGraphNode *CGGetValuePtr(const PairTy &P) {
491
    return P.second.get();
492
  }
493
494
  // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
495
  using nodes_iterator =
496
      mapped_iterator<CallGraph::const_iterator, decltype(&CGGetValuePtr)>;
497
498
  static nodes_iterator nodes_begin(const CallGraph *CG) {
499
    return nodes_iterator(CG->begin(), &CGGetValuePtr);
500
  }
501
502
  static nodes_iterator nodes_end(const CallGraph *CG) {
503
    return nodes_iterator(CG->end(), &CGGetValuePtr);
504
  }
505
};
506
507
} // end namespace llvm
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509
#endif // LLVM_ANALYSIS_CALLGRAPH_H