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
27namespace llvm {
28
29class CallGraphNode;
30class CallGraph;
31class PMStack;
32class CallGraphSCC;
33
34class CallGraphSCCPass : public Pass {
35public:
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.
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.
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
82/// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
83class CallGraphSCC {
84  void *Context; // The CGPassManager object that is vending this.
85  std::vector<CallGraphNode*> Nodes;
86public:
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