include/llvm/Analysis/CallGraphSCCPass.h

   1 //===- CallGraphSCCPass.h - Pass that operates BU on call graph -*- C++ -*-===//
   2 //
   3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
   4 // See https://llvm.org/LICENSE.txt for license information.
   5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
   6 //
   7 //===----------------------------------------------------------------------===//
   8 //
   9 // This file defines the CallGraphSCCPass class, which is used for passes which
  10 // are implemented as bottom-up traversals on the call graph.  Because there may
  11 // be cycles in the call graph, passes of this type operate on the call-graph in
  12 // SCC order: that is, they process function bottom-up, except for recursive
  13 // functions, which they process all at once.
  14 //
  15 // These passes are inherently interprocedural, and are required to keep the
  16 // call graph up-to-date if they do anything which could modify it.
  17 //
  18 //===----------------------------------------------------------------------===//
  19
  20 #ifndef LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
  21 #define LLVM_ANALYSIS_CALLGRAPHSCCPASS_H
  22
  23 #include "llvm/ADT/ArrayRef.h"
  24 #include "llvm/Pass.h"
  25 #include <vector>
  26
  27 namespace llvm {
  28
  29 class CallGraph;
  30 class CallGraphNode;
  31 class CallGraphSCC;
  32 class PMStack;
  33
  34 class CallGraphSCCPass : public Pass {
  35 public:
  36   explicit CallGraphSCCPass(char &pid) : Pass(PT_CallGraphSCC, pid) {}
  37
  38   /// createPrinterPass - Get a pass that prints the Module
  39   /// corresponding to a CallGraph.
  40   Pass *createPrinterPass(raw_ostream &OS,
  41                           const std::string &Banner) const override;
  42
  43   using llvm::Pass::doInitialization;
  44   using llvm::Pass::doFinalization;
  45
  46   /// doInitialization - This method is called before the SCC's of the program
  47   /// has been processed, allowing the pass to do initialization as necessary.
  48   virtual bool doInitialization(CallGraph &CG) {
  49     return false;
  50   }
  51
  52   /// runOnSCC - This method should be implemented by the subclass to perform
  53   /// whatever action is necessary for the specified SCC.  Note that
  54   /// non-recursive (or only self-recursive) functions will have an SCC size of
  55   /// 1, where recursive portions of the call graph will have SCC size > 1.
  56   ///
  57   /// SCC passes that add or delete functions to the SCC are required to update
  58   /// the SCC list, otherwise stale pointers may be dereferenced.
  59   virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
  60
  61   /// doFinalization - This method is called after the SCC's of the program has
  62   /// been processed, allowing the pass to do final cleanup as necessary.
  63   virtual bool doFinalization(CallGraph &CG) {
  64     return false;
  65   }
  66
  67   /// Assign pass manager to manager this pass
  68   void assignPassManager(PMStack &PMS, PassManagerType PMT) override;
  69
  70   ///  Return what kind of Pass Manager can manage this pass.
  71   PassManagerType getPotentialPassManagerType() const override {
  72     return PMT_CallGraphPassManager;
  73   }
  74
  75   /// getAnalysisUsage - For this class, we declare that we require and preserve
  76   /// the call graph.  If the derived class implements this method, it should
  77   /// always explicitly call the implementation here.
  78   void getAnalysisUsage(AnalysisUsage &Info) const override;
  79
  80 protected:
  81   /// Optional passes call this function to check whether the pass should be
  82   /// skipped. This is the case when optimization bisect is over the limit.
  83   bool skipSCC(CallGraphSCC &SCC) const;
  84 };
  85
  86 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
  87 class CallGraphSCC {
  88   const CallGraph &CG; // The call graph for this SCC.
  89   void *Context; // The CGPassManager object that is vending this.
  90   std::vector<CallGraphNode *> Nodes;
  91
  92 public:
  93   CallGraphSCC(CallGraph &cg, void *context) : CG(cg), Context(context) {}
  94
  95   void initialize(ArrayRef<CallGraphNode *> NewNodes) {
  96     Nodes.assign(NewNodes.begin(), NewNodes.end());
  97   }
  98
  99   bool isSingular() const { return Nodes.size() == 1; }
 100   unsigned size() const { return Nodes.size(); }
 101
 102   /// ReplaceNode - This informs the SCC and the pass manager that the specified
 103   /// Old node has been deleted, and New is to be used in its place.
 104   void ReplaceNode(CallGraphNode *Old, CallGraphNode *New);
 105
 106   using iterator = std::vector<CallGraphNode *>::const_iterator;
 107
 108   iterator begin() const { return Nodes.begin(); }
 109   iterator end() const { return Nodes.end(); }
 110
 111   const CallGraph &getCallGraph() { return CG; }
 112 };
 113
 114 void initializeDummyCGSCCPassPass(PassRegistry &);
 115
 116 /// This pass is required by interprocedural register allocation. It forces
 117 /// codegen to follow bottom up order on call graph.
 118 class DummyCGSCCPass : public CallGraphSCCPass {
 119 public:
 120   static char ID;
 121
 122   DummyCGSCCPass() : CallGraphSCCPass(ID) {
 123     PassRegistry &Registry = *PassRegistry::getPassRegistry();
 124     initializeDummyCGSCCPassPass(Registry);
 125   }
 126
 127   bool runOnSCC(CallGraphSCC &SCC) override { return false; }
 128
 129   void getAnalysisUsage(AnalysisUsage &AU) const override {
 130     AU.setPreservesAll();
 131   }
 132 };
 133
 134 } // end namespace llvm
 135
 136 #endif // LLVM_ANALYSIS_CALLGRAPHSCCPASS_H