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_CALL_GRAPH_SCC_PASS_H
22#define LLVM_CALL_GRAPH_SCC_PASS_H
23
24#include "llvm/Pass.h"
25#include "llvm/Analysis/CallGraph.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, const std::string &Banner) const;
41
42  /// doInitialization - This method is called before the SCC's of the program
43  /// has been processed, allowing the pass to do initialization as necessary.
44  virtual bool doInitialization(CallGraph &CG) {
45    return false;
46  }
47
48  /// runOnSCC - This method should be implemented by the subclass to perform
49  /// whatever action is necessary for the specified SCC.  Note that
50  /// non-recursive (or only self-recursive) functions will have an SCC size of
51  /// 1, where recursive portions of the call graph will have SCC size > 1.
52  ///
53  /// SCC passes that add or delete functions to the SCC are required to update
54  /// the SCC list, otherwise stale pointers may be dereferenced.
55  ///
56  virtual bool runOnSCC(CallGraphSCC &SCC) = 0;
57
58  /// doFinalization - This method is called after the SCC's of the program has
59  /// been processed, allowing the pass to do final cleanup as necessary.
60  virtual bool doFinalization(CallGraph &CG) {
61    return false;
62  }
63
64  /// Assign pass manager to manager this pass
65  virtual void assignPassManager(PMStack &PMS,
66                                 PassManagerType PMT);
67
68  ///  Return what kind of Pass Manager can manage this pass.
69  virtual PassManagerType getPotentialPassManagerType() const {
70    return PMT_CallGraphPassManager;
71  }
72
73  /// getAnalysisUsage - For this class, we declare that we require and preserve
74  /// the call graph.  If the derived class implements this method, it should
75  /// always explicitly call the implementation here.
76  virtual void getAnalysisUsage(AnalysisUsage &Info) const;
77};
78
79/// CallGraphSCC - This is a single SCC that a CallGraphSCCPass is run on.
80class CallGraphSCC {
81  void *Context; // The CGPassManager object that is vending this.
82  std::vector<CallGraphNode*> Nodes;
83public:
84  CallGraphSCC(void *context) : Context(context) {}
85
86  void initialize(CallGraphNode*const*I, CallGraphNode*const*E) {
87    Nodes.assign(I, E);
88  }
89
90  bool isSingular() const { return Nodes.size() == 1; }
91  unsigned size() const { return Nodes.size(); }
92
93  /// ReplaceNode - This informs the SCC and the pass manager that the specified
94  /// Old node has been deleted, and New is to be used in its place.
95  void ReplaceNode(CallGraphNode *Old, CallGraphNode *New);
96
97  typedef std::vector<CallGraphNode*>::const_iterator iterator;
98  iterator begin() const { return Nodes.begin(); }
99  iterator end() const { return Nodes.end(); }
100};
101
102} // End llvm namespace
103
104#endif
105