LCOV - code coverage report
Current view: top level - include/llvm/Analysis - CallGraph.h (source / functions) Hit Total Coverage
Test: llvm-toolchain.info Lines: 42 44 95.5 %
Date: 2017-09-14 15:23:50 Functions: 4 5 80.0 %
Legend: Lines: hit not hit

          Line data    Source code
       1             : //===- CallGraph.h - Build a Module's call graph ----------------*- C++ -*-===//
       2             : //
       3             : //                     The LLVM Compiler Infrastructure
       4             : //
       5             : // This file is distributed under the University of Illinois Open Source
       6             : // License. See LICENSE.TXT for details.
       7             : //
       8             : //===----------------------------------------------------------------------===//
       9             : /// \file
      10             : ///
      11             : /// This file provides interfaces used to build and manipulate a call graph,
      12             : /// which is a very useful tool for interprocedural optimization.
      13             : ///
      14             : /// Every function in a module is represented as a node in the call graph.  The
      15             : /// callgraph node keeps track of which functions are called by the function
      16             : /// corresponding to the node.
      17             : ///
      18             : /// A call graph may contain nodes where the function that they correspond to
      19             : /// is null.  These 'external' nodes are used to represent control flow that is
      20             : /// not represented (or analyzable) in the module.  In particular, this
      21             : /// analysis builds one external node such that:
      22             : ///   1. All functions in the module without internal linkage will have edges
      23             : ///      from this external node, indicating that they could be called by
      24             : ///      functions outside of the module.
      25             : ///   2. All functions whose address is used for something more than a direct
      26             : ///      call, for example being stored into a memory location will also have
      27             : ///      an edge from this external node.  Since they may be called by an
      28             : ///      unknown caller later, they must be tracked as such.
      29             : ///
      30             : /// There is a second external node added for calls that leave this module.
      31             : /// Functions have a call edge to the external node iff:
      32             : ///   1. The function is external, reflecting the fact that they could call
      33             : ///      anything without internal linkage or that has its address taken.
      34             : ///   2. The function contains an indirect function call.
      35             : ///
      36             : /// As an extension in the future, there may be multiple nodes with a null
      37             : /// function.  These will be used when we can prove (through pointer analysis)
      38             : /// that an indirect call site can call only a specific set of functions.
      39             : ///
      40             : /// Because of these properties, the CallGraph captures a conservative superset
      41             : /// of all of the caller-callee relationships, which is useful for
      42             : /// transformations.
      43             : ///
      44             : //===----------------------------------------------------------------------===//
      45             : 
      46             : #ifndef LLVM_ANALYSIS_CALLGRAPH_H
      47             : #define LLVM_ANALYSIS_CALLGRAPH_H
      48             : 
      49             : #include "llvm/ADT/GraphTraits.h"
      50             : #include "llvm/ADT/STLExtras.h"
      51             : #include "llvm/IR/CallSite.h"
      52             : #include "llvm/IR/Function.h"
      53             : #include "llvm/IR/Intrinsics.h"
      54             : #include "llvm/IR/PassManager.h"
      55             : #include "llvm/IR/ValueHandle.h"
      56             : #include "llvm/Pass.h"
      57             : #include <cassert>
      58             : #include <map>
      59             : #include <memory>
      60             : #include <utility>
      61             : #include <vector>
      62             : 
      63             : namespace llvm {
      64             : 
      65             : class CallGraphNode;
      66             : class Module;
      67             : class raw_ostream;
      68             : 
      69             : /// \brief The basic data container for the call graph of a \c Module of IR.
      70             : ///
      71             : /// This class exposes both the interface to the call graph for a module of IR.
      72             : ///
      73             : /// The core call graph itself can also be updated to reflect changes to the IR.
      74             : class CallGraph {
      75             :   Module &M;
      76             : 
      77             :   using FunctionMapTy =
      78             :       std::map<const Function *, std::unique_ptr<CallGraphNode>>;
      79             : 
      80             :   /// \brief A map from \c Function* to \c CallGraphNode*.
      81             :   FunctionMapTy FunctionMap;
      82             : 
      83             :   /// \brief This node has edges to all external functions and those internal
      84             :   /// functions that have their address taken.
      85             :   CallGraphNode *ExternalCallingNode;
      86             : 
      87             :   /// \brief This node has edges to it from all functions making indirect calls
      88             :   /// or calling an external function.
      89             :   std::unique_ptr<CallGraphNode> CallsExternalNode;
      90             : 
      91             :   /// \brief Replace the function represented by this node by another.
      92             :   ///
      93             :   /// This does not rescan the body of the function, so it is suitable when
      94             :   /// splicing the body of one function to another while also updating all
      95             :   /// callers from the old function to the new.
      96             :   void spliceFunction(const Function *From, const Function *To);
      97             : 
      98             :   /// \brief Add a function to the call graph, and link the node to all of the
      99             :   /// functions that it calls.
     100             :   void addToCallGraph(Function *F);
     101             : 
     102             : public:
     103             :   explicit CallGraph(Module &M);
     104             :   CallGraph(CallGraph &&Arg);
     105             :   ~CallGraph();
     106             : 
     107             :   void print(raw_ostream &OS) const;
     108             :   void dump() const;
     109             : 
     110             :   using iterator = FunctionMapTy::iterator;
     111             :   using const_iterator = FunctionMapTy::const_iterator;
     112             : 
     113             :   /// \brief Returns the module the call graph corresponds to.
     114             :   Module &getModule() const { return M; }
     115             : 
     116       15426 :   inline iterator begin() { return FunctionMap.begin(); }
     117       15426 :   inline iterator end() { return FunctionMap.end(); }
     118          14 :   inline const_iterator begin() const { return FunctionMap.begin(); }
     119          14 :   inline const_iterator end() const { return FunctionMap.end(); }
     120             : 
     121             :   /// \brief Returns the call graph node for the provided function.
     122             :   inline const CallGraphNode *operator[](const Function *F) const {
     123             :     const_iterator I = FunctionMap.find(F);
     124             :     assert(I != FunctionMap.end() && "Function not in callgraph!");
     125             :     return I->second.get();
     126             :   }
     127             : 
     128             :   /// \brief Returns the call graph node for the provided function.
     129             :   inline CallGraphNode *operator[](const Function *F) {
     130      697448 :     const_iterator I = FunctionMap.find(F);
     131             :     assert(I != FunctionMap.end() && "Function not in callgraph!");
     132      478334 :     return I->second.get();
     133             :   }
     134             : 
     135             :   /// \brief Returns the \c CallGraphNode which is used to represent
     136             :   /// undetermined calls into the callgraph.
     137             :   CallGraphNode *getExternalCallingNode() const { return ExternalCallingNode; }
     138             : 
     139             :   CallGraphNode *getCallsExternalNode() const {
     140         110 :     return CallsExternalNode.get();
     141             :   }
     142             : 
     143             :   //===---------------------------------------------------------------------
     144             :   // Functions to keep a call graph up to date with a function that has been
     145             :   // modified.
     146             :   //
     147             : 
     148             :   /// \brief Unlink the function from this module, returning it.
     149             :   ///
     150             :   /// Because this removes the function from the module, the call graph node is
     151             :   /// destroyed.  This is only valid if the function does not call any other
     152             :   /// functions (ie, there are no edges in it's CGN).  The easiest way to do
     153             :   /// this is to dropAllReferences before calling this.
     154             :   Function *removeFunctionFromModule(CallGraphNode *CGN);
     155             : 
     156             :   /// \brief Similar to operator[], but this will insert a new CallGraphNode for
     157             :   /// \c F if one does not already exist.
     158             :   CallGraphNode *getOrInsertFunction(const Function *F);
     159             : };
     160             : 
     161             : /// \brief A node in the call graph for a module.
     162             : ///
     163             : /// Typically represents a function in the call graph. There are also special
     164             : /// "null" nodes used to represent theoretical entries in the call graph.
     165             : class CallGraphNode {
     166             : public:
     167             :   /// \brief A pair of the calling instruction (a call or invoke)
     168             :   /// and the call graph node being called.
     169             :   using CallRecord = std::pair<WeakTrackingVH, CallGraphNode *>;
     170             : 
     171             : public:
     172             :   using CalledFunctionsVector = std::vector<CallRecord>;
     173             : 
     174             :   /// \brief Creates a node for the specified function.
     175      424698 :   inline CallGraphNode(Function *F) : F(F) {}
     176             : 
     177             :   CallGraphNode(const CallGraphNode &) = delete;
     178             :   CallGraphNode &operator=(const CallGraphNode &) = delete;
     179             : 
     180      212322 :   ~CallGraphNode() {
     181             :     assert(NumReferences == 0 && "Node deleted while references remain");
     182             :   }
     183             : 
     184             :   using iterator = std::vector<CallRecord>::iterator;
     185             :   using const_iterator = std::vector<CallRecord>::const_iterator;
     186             : 
     187             :   /// \brief Returns the function that this call graph node represents.
     188             :   Function *getFunction() const { return F; }
     189             : 
     190      974456 :   inline iterator begin() { return CalledFunctions.begin(); }
     191     3942690 :   inline iterator end() { return CalledFunctions.end(); }
     192          20 :   inline const_iterator begin() const { return CalledFunctions.begin(); }
     193          20 :   inline const_iterator end() const { return CalledFunctions.end(); }
     194             :   inline bool empty() const { return CalledFunctions.empty(); }
     195             :   inline unsigned size() const { return (unsigned)CalledFunctions.size(); }
     196             : 
     197             :   /// \brief Returns the number of other CallGraphNodes in this CallGraph that
     198             :   /// reference this node in their callee list.
     199             :   unsigned getNumReferences() const { return NumReferences; }
     200             : 
     201             :   /// \brief Returns the i'th called function.
     202             :   CallGraphNode *operator[](unsigned i) const {
     203             :     assert(i < CalledFunctions.size() && "Invalid index");
     204             :     return CalledFunctions[i].second;
     205             :   }
     206             : 
     207             :   /// \brief Print out this call graph node.
     208             :   void dump() const;
     209             :   void print(raw_ostream &OS) const;
     210             : 
     211             :   //===---------------------------------------------------------------------
     212             :   // Methods to keep a call graph up to date with a function that has been
     213             :   // modified
     214             :   //
     215             : 
     216             :   /// \brief Removes all edges from this CallGraphNode to any functions it
     217             :   /// calls.
     218             :   void removeAllCalledFunctions() {
     219      111700 :     while (!CalledFunctions.empty()) {
     220       35096 :       CalledFunctions.back().second->DropRef();
     221       17548 :       CalledFunctions.pop_back();
     222             :     }
     223             :   }
     224             : 
     225             :   /// \brief Moves all the callee information from N to this node.
     226             :   void stealCalledFunctionsFrom(CallGraphNode *N) {
     227             :     assert(CalledFunctions.empty() &&
     228             :            "Cannot steal callsite information if I already have some");
     229          84 :     std::swap(CalledFunctions, N->CalledFunctions);
     230             :   }
     231             : 
     232             :   /// \brief Adds a function to the list of functions called by this one.
     233             :   void addCalledFunction(CallSite CS, CallGraphNode *M) {
     234             :     assert(!CS.getInstruction() || !CS.getCalledFunction() ||
     235             :            !CS.getCalledFunction()->isIntrinsic() ||
     236             :            !Intrinsic::isLeaf(CS.getCalledFunction()->getIntrinsicID()));
     237     1375684 :     CalledFunctions.emplace_back(CS.getInstruction(), M);
     238      687842 :     M->AddRef();
     239             :   }
     240             : 
     241        4468 :   void removeCallEdge(iterator I) {
     242        4468 :     I->second->DropRef();
     243       13404 :     *I = CalledFunctions.back();
     244        4468 :     CalledFunctions.pop_back();
     245        4468 :   }
     246             : 
     247             :   /// \brief Removes the edge in the node for the specified call site.
     248             :   ///
     249             :   /// Note that this method takes linear time, so it should be used sparingly.
     250             :   void removeCallEdgeFor(CallSite CS);
     251             : 
     252             :   /// \brief Removes all call edges from this node to the specified callee
     253             :   /// function.
     254             :   ///
     255             :   /// This takes more time to execute than removeCallEdgeTo, so it should not
     256             :   /// be used unless necessary.
     257             :   void removeAnyCallEdgeTo(CallGraphNode *Callee);
     258             : 
     259             :   /// \brief Removes one edge associated with a null callsite from this node to
     260             :   /// the specified callee function.
     261             :   void removeOneAbstractEdgeTo(CallGraphNode *Callee);
     262             : 
     263             :   /// \brief Replaces the edge in the node for the specified call site with a
     264             :   /// new one.
     265             :   ///
     266             :   /// Note that this method takes linear time, so it should be used sparingly.
     267             :   void replaceCallEdge(CallSite CS, CallSite NewCS, CallGraphNode *NewNode);
     268             : 
     269             : private:
     270             :   friend class CallGraph;
     271             : 
     272             :   Function *F;
     273             : 
     274             :   std::vector<CallRecord> CalledFunctions;
     275             : 
     276             :   /// \brief The number of times that this CallGraphNode occurs in the
     277             :   /// CalledFunctions array of this or other CallGraphNodes.
     278             :   unsigned NumReferences = 0;
     279             : 
     280      128599 :   void DropRef() { --NumReferences; }
     281      687936 :   void AddRef() { ++NumReferences; }
     282             : 
     283             :   /// \brief A special function that should only be used by the CallGraph class.
     284       11166 :   void allReferencesDropped() { NumReferences = 0; }
     285             : };
     286             : 
     287             : /// \brief An analysis pass to compute the \c CallGraph for a \c Module.
     288             : ///
     289             : /// This class implements the concept of an analysis pass used by the \c
     290             : /// ModuleAnalysisManager to run an analysis over a module and cache the
     291             : /// resulting data.
     292             : class CallGraphAnalysis : public AnalysisInfoMixin<CallGraphAnalysis> {
     293             :   friend AnalysisInfoMixin<CallGraphAnalysis>;
     294             : 
     295             :   static AnalysisKey Key;
     296             : 
     297             : public:
     298             :   /// \brief A formulaic type to inform clients of the result type.
     299             :   using Result = CallGraph;
     300             : 
     301             :   /// \brief Compute the \c CallGraph for the module \c M.
     302             :   ///
     303             :   /// The real work here is done in the \c CallGraph constructor.
     304          91 :   CallGraph run(Module &M, ModuleAnalysisManager &) { return CallGraph(M); }
     305             : };
     306             : 
     307             : /// \brief Printer pass for the \c CallGraphAnalysis results.
     308             : class CallGraphPrinterPass : public PassInfoMixin<CallGraphPrinterPass> {
     309             :   raw_ostream &OS;
     310             : 
     311             : public:
     312           1 :   explicit CallGraphPrinterPass(raw_ostream &OS) : OS(OS) {}
     313             : 
     314             :   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
     315             : };
     316             : 
     317             : /// \brief The \c ModulePass which wraps up a \c CallGraph and the logic to
     318             : /// build it.
     319             : ///
     320             : /// This class exposes both the interface to the call graph container and the
     321             : /// module pass which runs over a module of IR and produces the call graph. The
     322             : /// call graph interface is entirelly a wrapper around a \c CallGraph object
     323             : /// which is stored internally for each module.
     324       22124 : class CallGraphWrapperPass : public ModulePass {
     325             :   std::unique_ptr<CallGraph> G;
     326             : 
     327             : public:
     328             :   static char ID; // Class identification, replacement for typeinfo
     329             : 
     330             :   CallGraphWrapperPass();
     331             :   ~CallGraphWrapperPass() override;
     332             : 
     333             :   /// \brief The internal \c CallGraph around which the rest of this interface
     334             :   /// is wrapped.
     335             :   const CallGraph &getCallGraph() const { return *G; }
     336      438226 :   CallGraph &getCallGraph() { return *G; }
     337             : 
     338             :   using iterator = CallGraph::iterator;
     339             :   using const_iterator = CallGraph::const_iterator;
     340             : 
     341             :   /// \brief Returns the module the call graph corresponds to.
     342             :   Module &getModule() const { return G->getModule(); }
     343             : 
     344             :   inline iterator begin() { return G->begin(); }
     345             :   inline iterator end() { return G->end(); }
     346             :   inline const_iterator begin() const { return G->begin(); }
     347             :   inline const_iterator end() const { return G->end(); }
     348             : 
     349             :   /// \brief Returns the call graph node for the provided function.
     350             :   inline const CallGraphNode *operator[](const Function *F) const {
     351             :     return (*G)[F];
     352             :   }
     353             : 
     354             :   /// \brief Returns the call graph node for the provided function.
     355             :   inline CallGraphNode *operator[](const Function *F) { return (*G)[F]; }
     356             : 
     357             :   /// \brief Returns the \c CallGraphNode which is used to represent
     358             :   /// undetermined calls into the callgraph.
     359             :   CallGraphNode *getExternalCallingNode() const {
     360             :     return G->getExternalCallingNode();
     361             :   }
     362             : 
     363             :   CallGraphNode *getCallsExternalNode() const {
     364             :     return G->getCallsExternalNode();
     365             :   }
     366             : 
     367             :   //===---------------------------------------------------------------------
     368             :   // Functions to keep a call graph up to date with a function that has been
     369             :   // modified.
     370             :   //
     371             : 
     372             :   /// \brief 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             :   Function *removeFunctionFromModule(CallGraphNode *CGN) {
     379             :     return G->removeFunctionFromModule(CGN);
     380             :   }
     381             : 
     382             :   /// \brief Similar to operator[], but this will insert a new CallGraphNode for
     383             :   /// \c F if one does not already exist.
     384             :   CallGraphNode *getOrInsertFunction(const Function *F) {
     385             :     return G->getOrInsertFunction(F);
     386             :   }
     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             : //
     404             : 
     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     1480272 :   static CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
     413             : 
     414             :   using ChildIteratorType =
     415             :       mapped_iterator<CallGraphNode::iterator, decltype(&CGNGetValue)>;
     416             : 
     417             :   static ChildIteratorType child_begin(NodeRef N) {
     418      328418 :     return ChildIteratorType(N->begin(), &CGNGetValue);
     419             :   }
     420             : 
     421             :   static ChildIteratorType child_end(NodeRef N) {
     422     1808690 :     return ChildIteratorType(N->end(), &CGNGetValue);
     423             :   }
     424             : };
     425             : 
     426             : template <> struct GraphTraits<const CallGraphNode *> {
     427             :   using NodeRef = const CallGraphNode *;
     428             :   using CGNPairTy = CallGraphNode::CallRecord;
     429             : 
     430             :   static NodeRef getEntryNode(const CallGraphNode *CGN) { return CGN; }
     431             :   static const CallGraphNode *CGNGetValue(CGNPairTy P) { return P.second; }
     432             : 
     433             :   using ChildIteratorType =
     434             :       mapped_iterator<CallGraphNode::const_iterator, decltype(&CGNGetValue)>;
     435             : 
     436             :   static ChildIteratorType child_begin(NodeRef N) {
     437           1 :     return ChildIteratorType(N->begin(), &CGNGetValue);
     438             :   }
     439             : 
     440             :   static ChildIteratorType child_end(NodeRef N) {
     441           1 :     return ChildIteratorType(N->end(), &CGNGetValue);
     442             :   }
     443             : };
     444             : 
     445             : template <>
     446             : struct GraphTraits<CallGraph *> : public GraphTraits<CallGraphNode *> {
     447             :   using PairTy =
     448             :       std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
     449             : 
     450             :   static NodeRef getEntryNode(CallGraph *CGN) {
     451       15284 :     return CGN->getExternalCallingNode(); // Start at the external node!
     452             :   }
     453             : 
     454           0 :   static CallGraphNode *CGGetValuePtr(const PairTy &P) {
     455           0 :     return P.second.get();
     456             :   }
     457             : 
     458             :   // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
     459             :   using nodes_iterator =
     460             :       mapped_iterator<CallGraph::iterator, decltype(&CGGetValuePtr)>;
     461             : 
     462             :   static nodes_iterator nodes_begin(CallGraph *CG) {
     463           1 :     return nodes_iterator(CG->begin(), &CGGetValuePtr);
     464             :   }
     465             : 
     466             :   static nodes_iterator nodes_end(CallGraph *CG) {
     467           1 :     return nodes_iterator(CG->end(), &CGGetValuePtr);
     468             :   }
     469             : };
     470             : 
     471             : template <>
     472             : struct GraphTraits<const CallGraph *> : public GraphTraits<
     473             :                                             const CallGraphNode *> {
     474             :   using PairTy =
     475             :       std::pair<const Function *const, std::unique_ptr<CallGraphNode>>;
     476             : 
     477             :   static NodeRef getEntryNode(const CallGraph *CGN) {
     478           1 :     return CGN->getExternalCallingNode(); // Start at the external node!
     479             :   }
     480             : 
     481             :   static const CallGraphNode *CGGetValuePtr(const PairTy &P) {
     482             :     return P.second.get();
     483             :   }
     484             : 
     485             :   // nodes_iterator/begin/end - Allow iteration over all nodes in the graph
     486             :   using nodes_iterator =
     487             :       mapped_iterator<CallGraph::const_iterator, decltype(&CGGetValuePtr)>;
     488             : 
     489             :   static nodes_iterator nodes_begin(const CallGraph *CG) {
     490           1 :     return nodes_iterator(CG->begin(), &CGGetValuePtr);
     491             :   }
     492             : 
     493             :   static nodes_iterator nodes_end(const CallGraph *CG) {
     494           1 :     return nodes_iterator(CG->end(), &CGGetValuePtr);
     495             :   }
     496             : };
     497             : 
     498             : } // end namespace llvm
     499             : 
     500             : #endif // LLVM_ANALYSIS_CALLGRAPH_H

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