LLVM  6.0.0svn
DeltaAlgorithm.h
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1 //===- DeltaAlgorithm.h - A Set Minimization Algorithm ---------*- 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 #ifndef LLVM_ADT_DELTAALGORITHM_H
10 #define LLVM_ADT_DELTAALGORITHM_H
11 
12 #include <set>
13 #include <vector>
14 
15 namespace llvm {
16 
17 /// DeltaAlgorithm - Implements the delta debugging algorithm (A. Zeller '99)
18 /// for minimizing arbitrary sets using a predicate function.
19 ///
20 /// The result of the algorithm is a subset of the input change set which is
21 /// guaranteed to satisfy the predicate, assuming that the input set did. For
22 /// well formed predicates, the result set is guaranteed to be such that
23 /// removing any single element would falsify the predicate.
24 ///
25 /// For best results the predicate function *should* (but need not) satisfy
26 /// certain properties, in particular:
27 /// (1) The predicate should return false on an empty set and true on the full
28 /// set.
29 /// (2) If the predicate returns true for a set of changes, it should return
30 /// true for all supersets of that set.
31 ///
32 /// It is not an error to provide a predicate that does not satisfy these
33 /// requirements, and the algorithm will generally produce reasonable
34 /// results. However, it may run substantially more tests than with a good
35 /// predicate.
37 public:
39  // FIXME: Use a decent data structure.
40  using changeset_ty = std::set<change_ty>;
41  using changesetlist_ty = std::vector<changeset_ty>;
42 
43 private:
44  /// Cache of failed test results. Successful test results are never cached
45  /// since we always reduce following a success.
46  std::set<changeset_ty> FailedTestsCache;
47 
48  /// GetTestResult - Get the test result for the \p Changes from the
49  /// cache, executing the test if necessary.
50  ///
51  /// \param Changes - The change set to test.
52  /// \return - The test result.
53  bool GetTestResult(const changeset_ty &Changes);
54 
55  /// Split - Partition a set of changes \p S into one or two subsets.
56  void Split(const changeset_ty &S, changesetlist_ty &Res);
57 
58  /// Delta - Minimize a set of \p Changes which has been partioned into
59  /// smaller sets, by attempting to remove individual subsets.
60  changeset_ty Delta(const changeset_ty &Changes,
61  const changesetlist_ty &Sets);
62 
63  /// Search - Search for a subset (or subsets) in \p Sets which can be
64  /// removed from \p Changes while still satisfying the predicate.
65  ///
66  /// \param Res - On success, a subset of Changes which satisfies the
67  /// predicate.
68  /// \return - True on success.
69  bool Search(const changeset_ty &Changes, const changesetlist_ty &Sets,
70  changeset_ty &Res);
71 
72 protected:
73  /// UpdatedSearchState - Callback used when the search state changes.
74  virtual void UpdatedSearchState(const changeset_ty &Changes,
75  const changesetlist_ty &Sets) {}
76 
77  /// ExecuteOneTest - Execute a single test predicate on the change set \p S.
78  virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
79 
80  DeltaAlgorithm& operator=(const DeltaAlgorithm&) = default;
81 
82 public:
83  virtual ~DeltaAlgorithm();
84 
85  /// Run - Minimize the set \p Changes by executing \see ExecuteOneTest() on
86  /// subsets of changes and returning the smallest set which still satisfies
87  /// the test predicate.
88  changeset_ty Run(const changeset_ty &Changes);
89 };
90 
91 } // end namespace llvm
92 
93 #endif // LLVM_ADT_DELTAALGORITHM_H
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
virtual void UpdatedSearchState(const changeset_ty &Changes, const changesetlist_ty &Sets)
UpdatedSearchState - Callback used when the search state changes.
std::set< change_ty > changeset_ty
DeltaAlgorithm - Implements the delta debugging algorithm (A.
DeltaAlgorithm & operator=(const DeltaAlgorithm &)=default
changeset_ty Run(const changeset_ty &Changes)
Run - Minimize the set Changes by executing.
std::vector< changeset_ty > changesetlist_ty
virtual bool ExecuteOneTest(const changeset_ty &S)=0
ExecuteOneTest - Execute a single test predicate on the change set S.