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:
CallGraphSCCPass(char & pid)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,
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.
doInitialization(CallGraph & CG)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   ///
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.
doFinalization(CallGraph & CG)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.
getPotentialPassManagerType()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 
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:
CallGraphSCC(void * context)87   CallGraphSCC(void *context) : Context(context) {}
88 
initialize(CallGraphNode * const * I,CallGraphNode * const * E)89   void initialize(CallGraphNode*const*I, CallGraphNode*const*E) {
90     Nodes.assign(I, E);
91   }
92 
isSingular()93   bool isSingular() const { return Nodes.size() == 1; }
size()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;
begin()101   iterator begin() const { return Nodes.begin(); }
end()102   iterator end() const { return Nodes.end(); }
103 };
104 
105 } // End llvm namespace
106 
107 #endif
108