include/llvm/Analysis/CallGraphSCCPass.h

   1 //===- CallGraphSCCPass.h - Pass that operates BU on 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 //
  10 // This file defines the CallGraphSCCPass class, which is used for passes which
  11 // are implemented as bottom-up traversals on the call graph.  Because there may
  12 // be cycles in the call graph, passes of this type operate on the call-graph in
  13 // SCC order: that is, they process function bottom-up, except for recursive
  14 // functions, which they process all at once.
  15 //
  16 // These passes are inherently interprocedural, and are required to keep the
  17 // call graph up-to-date if they do anything which could modify it.
  18 //
  19 //===----------------------------------------------------------------------===//
  20
  21 #ifndef LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
  22 #define LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
  23
  24 #include "llvm/ADT/ArrayRef.h"
  25 #include "llvm/Pass.h"
  26 #include <vector>
  27
  28 namespace llvm {
  29
  30 class CallGraph;
  31 class CallGraphNode;
  32 class CallGraphSCC;
  33 class PMStack;
  34
  35 class CallGraphSCCPass : public Pass {
  36 public:
  37   explicit CallGraphSCCPass(char &pid) : Pass(PT_CallGraphSCC, pid) {}
  38
  39   /// createPrinterPass - Get a pass that prints the Module
  40   /// corresponding to a CallGraph.
  41   Pass *createPrinterPass(raw_ostream &OS,
  42                           const std::string &Banner) const override;
  43
  44   using llvm::Pass::doInitialization;
  45   using llvm::Pass::doFinalization;
  46
  47   /// doInitialization - This method is called before the SCC's of the program
  48   /// has been processed, allowing the pass to do initialization as necessary.
  49   virtual bool doInitialization(CallGraph &CG) {
  50     return false;
  51   }
  52
  53   /// runOnSCC - This method should be implemented by the subclass to perform
  54   /// whatever action is necessary for the specified SCC.  Note that
  55   /// non-recursive (or only self-recursive) functions will have an SCC size of
  56   /// 1, where recursive portions of the call graph will have SCC size > 1.
  57   ///
  58   /// SCC passes that add or delete functions to the SCC are required to update
  59   /// the SCC list, otherwise stale pointers may be dereferenced.
  60   virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
  61
  62   /// doFinalization - This method is called after the SCC's of the program has
  63   /// been processed, allowing the pass to do final cleanup as necessary.
  64   virtual bool doFinalization(CallGraph &CG) {
  65     return false;
  66   }
  67
  68   /// Assign pass manager to manager this pass
  69   void assignPassManager(PMStack &PMS, PassManagerType PMT) override;
  70
  71   ///  Return what kind of Pass Manager can manage this pass.
  72   PassManagerType getPotentialPassManagerType() const override {
  73     return PMT_CallGraphPassManager;
  74   }
  75
  76   /// getAnalysisUsage - For this class, we declare that we require and preserve
  77   /// the call graph.  If the derived class implements this method, it should
  78   /// always explicitly call the implementation here.
  79   void getAnalysisUsage(AnalysisUsage &Info) const override;
  80
  81 protected:
  82   /// Optional passes call this function to check whether the pass should be
  83   /// skipped. This is the case when optimization bisect is over the limit.
  84   bool skipSCC(CallGraphSCC &SCC) const;
  85 };
  86
  87 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
  88 class CallGraphSCC {
  89   const CallGraph &CG; // The call graph for this SCC.
  90   void *Context; // The CGPassManager object that is vending this.
  91   std::vector<CallGraphNode *> Nodes;
  92
  93 public:
  94   CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {}
  95
  96   void initialize(ArrayRef<CallGraphNode *> NewNodes) {
  97     Nodes.assign(NewNodes.begin(), NewNodes.end());
  98   }
  99
 100   bool isSingular() const { return Nodes.size() == 1; }
 101   unsigned size() const { return Nodes.size(); }
 102
 103   /// ReplaceNode - This informs the SCC and the pass manager that the specified
 104   /// Old node has been deleted, and New is to be used in its place.
 105   void ReplaceNode(CallGraphNode *Old, CallGraphNode *New);
 106
 107   using iterator = std::vector<CallGraphNode *>::const_iterator;
 108
 109   iterator begin() const { return Nodes.begin(); }
 110   iterator end() const { return Nodes.end(); }
 111
 112   const CallGraph &getCallGraph() { return CG; }
 113 };
 114
 115 void initializeDummyCGSCCPassPass(PassRegistry &);
 116
 117 /// This pass is required by interprocedural register allocation. It forces
 118 /// codegen to follow bottom up order on call graph.
 119 class DummyCGSCCPass : public CallGraphSCCPass {
 120 public:
 121   static char ID;
 122
 123   DummyCGSCCPass() : CallGraphSCCPass(ID) {
 124     PassRegistry &Registry = *PassRegistry::getPassRegistry();
 125     initializeDummyCGSCCPassPass(Registry);
 126   }
 127
 128   bool runOnSCC(CallGraphSCC &SCC) override { return false; }
 129
 130   void getAnalysisUsage(AnalysisUsage &AU) const override {
 131     AU.setPreservesAll();
 132   }
 133 };
 134
 135 } // end namespace llvm
 136
 137 #endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H