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DAGDeltaAlgorithm.h
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1 //===- DAGDeltaAlgorithm.h - A DAG 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_DAGDELTAALGORITHM_H
10 #define LLVM_ADT_DAGDELTAALGORITHM_H
11 
12 #include <set>
13 #include <utility>
14 #include <vector>
15 
16 namespace llvm {
17 
18 /// DAGDeltaAlgorithm - Implements a "delta debugging" algorithm for minimizing
19 /// directed acyclic graphs using a predicate function.
20 ///
21 /// The result of the algorithm is a subset of the input change set which is
22 /// guaranteed to satisfy the predicate, assuming that the input set did. For
23 /// well formed predicates, the result set is guaranteed to be such that
24 /// removing any single element not required by the dependencies on the other
25 /// elements would falsify the predicate.
26 ///
27 /// The DAG should be used to represent dependencies in the changes which are
28 /// likely to hold across the predicate function. That is, for a particular
29 /// changeset S and predicate P:
30 ///
31 /// P(S) => P(S union pred(S))
32 ///
33 /// The minization algorithm uses this dependency information to attempt to
34 /// eagerly prune large subsets of changes. As with \see DeltaAlgorithm, the DAG
35 /// is not required to satisfy this property, but the algorithm will run
36 /// substantially fewer tests with appropriate dependencies. \see DeltaAlgorithm
37 /// for more information on the properties which the predicate function itself
38 /// should satisfy.
40  virtual void anchor();
41 
42 public:
44  using edge_ty = std::pair<change_ty, change_ty>;
45 
46  // FIXME: Use a decent data structure.
47  using changeset_ty = std::set<change_ty>;
48  using changesetlist_ty = std::vector<changeset_ty>;
49 
50 public:
51  virtual ~DAGDeltaAlgorithm() = default;
52 
53  /// Run - Minimize the DAG formed by the \p Changes vertices and the
54  /// \p Dependencies edges by executing \see ExecuteOneTest() on subsets of
55  /// changes and returning the smallest set which still satisfies the test
56  /// predicate and the input \p Dependencies.
57  ///
58  /// \param Changes The list of changes.
59  ///
60  /// \param Dependencies The list of dependencies amongst changes. For each
61  /// (x,y) in \p Dependencies, both x and y must be in \p Changes. The
62  /// minimization algorithm guarantees that for each tested changed set S,
63  /// \f$ x \in S \f$ implies \f$ y \in S \f$. It is an error to have cyclic
64  /// dependencies.
65  changeset_ty Run(const changeset_ty &Changes,
66  const std::vector<edge_ty> &Dependencies);
67 
68  /// UpdatedSearchState - Callback used when the search state changes.
69  virtual void UpdatedSearchState(const changeset_ty &Changes,
70  const changesetlist_ty &Sets,
71  const changeset_ty &Required) {}
72 
73  /// ExecuteOneTest - Execute a single test predicate on the change set \p S.
74  virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
75 };
76 
77 } // end namespace llvm
78 
79 #endif // LLVM_ADT_DAGDELTAALGORITHM_H
DAGDeltaAlgorithm - Implements a "delta debugging" algorithm for minimizing directed acyclic graphs u...
Compute iterated dominance frontiers using a linear time algorithm.
Definition: AllocatorList.h:24
std::set< change_ty > changeset_ty
virtual ~DAGDeltaAlgorithm()=default
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.
std::pair< change_ty, change_ty > edge_ty
changeset_ty Run(const changeset_ty &Changes, const std::vector< edge_ty > &Dependencies)
Run - Minimize the DAG formed by the Changes vertices and the Dependencies edges by executing...
virtual void UpdatedSearchState(const changeset_ty &Changes, const changesetlist_ty &Sets, const changeset_ty &Required)
UpdatedSearchState - Callback used when the search state changes.