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      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/Analysis/CallGraph.h"
     25 #include "llvm/Pass.h"
     26 
     27 namespace llvm {
     28 
     29 class CallGraphNode;
     30 class CallGraph;
     31 class PMStack;
     32 class CallGraphSCC;
     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 &O, const std::string &Banner) const;
     41 
     42   using llvm::Pass::doInitialization;
     43   using llvm::Pass::doFinalization;
     44 
     45   /// doInitialization - This method is called before the SCC's of the program
     46   /// has been processed, allowing the pass to do initialization as necessary.
     47   virtual bool doInitialization(CallGraph &CG) {
     48     return false;
     49   }
     50 
     51   /// runOnSCC - This method should be implemented by the subclass to perform
     52   /// whatever action is necessary for the specified SCC.  Note that
     53   /// non-recursive (or only self-recursive) functions will have an SCC size of
     54   /// 1, where recursive portions of the call graph will have SCC size > 1.
     55   ///
     56   /// SCC passes that add or delete functions to the SCC are required to update
     57   /// the SCC list, otherwise stale pointers may be dereferenced.
     58   ///
     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   virtual void assignPassManager(PMStack &PMS,
     69                                  PassManagerType PMT);
     70 
     71   ///  Return what kind of Pass Manager can manage this pass.
     72   virtual PassManagerType getPotentialPassManagerType() const {
     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   virtual void getAnalysisUsage(AnalysisUsage &Info) const;
     80 };
     81 
     82 /// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
     83 class CallGraphSCC {
     84   void *Context; // The CGPassManager object that is vending this.
     85   std::vector<CallGraphNode*> Nodes;
     86 public:
     87   CallGraphSCC(void *context) : Context(context) {}
     88 
     89   void initialize(CallGraphNode*const*I, CallGraphNode*const*E) {
     90     Nodes.assign(I, E);
     91   }
     92 
     93   bool isSingular() const { return Nodes.size() == 1; }
     94   unsigned size() const { return Nodes.size(); }
     95 
     96   /// ReplaceNode - This informs the SCC and the pass manager that the specified
     97   /// Old node has been deleted, and New is to be used in its place.
     98   void ReplaceNode(CallGraphNode *Old, CallGraphNode *New);
     99 
    100   typedef std::vector<CallGraphNode*>::const_iterator iterator;
    101   iterator begin() const { return Nodes.begin(); }
    102   iterator end() const { return Nodes.end(); }
    103 };
    104 
    105 } // End llvm namespace
    106 
    107 #endif
    108