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DAGDeltaAlgorithm.h
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1 //===- DAGDeltaAlgorithm.h - A DAG Minimization Algorithm ------*- C++ -*--===//
2 //
3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
4 // See https://llvm.org/LICENSE.txt for license information.
5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
6 //===----------------------------------------------------------------------===//
7 
8 #ifndef LLVM_ADT_DAGDELTAALGORITHM_H
9 #define LLVM_ADT_DAGDELTAALGORITHM_H
10 
11 #include <set>
12 #include <utility>
13 #include <vector>
14 
15 namespace llvm {
16 
17 /// DAGDeltaAlgorithm - Implements a "delta debugging" algorithm for minimizing
18 /// directed acyclic graphs 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 not required by the dependencies on the other
24 /// elements would falsify the predicate.
25 ///
26 /// The DAG should be used to represent dependencies in the changes which are
27 /// likely to hold across the predicate function. That is, for a particular
28 /// changeset S and predicate P:
29 ///
30 /// P(S) => P(S union pred(S))
31 ///
32 /// The minization algorithm uses this dependency information to attempt to
33 /// eagerly prune large subsets of changes. As with \see DeltaAlgorithm, the DAG
34 /// is not required to satisfy this property, but the algorithm will run
35 /// substantially fewer tests with appropriate dependencies. \see DeltaAlgorithm
36 /// for more information on the properties which the predicate function itself
37 /// should satisfy.
39  virtual void anchor();
40 
41 public:
43  using edge_ty = std::pair<change_ty, change_ty>;
44 
45  // FIXME: Use a decent data structure.
46  using changeset_ty = std::set<change_ty>;
47  using changesetlist_ty = std::vector<changeset_ty>;
48 
49 public:
50  virtual ~DAGDeltaAlgorithm() = default;
51 
52  /// Run - Minimize the DAG formed by the \p Changes vertices and the
53  /// \p Dependencies edges by executing \see ExecuteOneTest() on subsets of
54  /// changes and returning the smallest set which still satisfies the test
55  /// predicate and the input \p Dependencies.
56  ///
57  /// \param Changes The list of changes.
58  ///
59  /// \param Dependencies The list of dependencies amongst changes. For each
60  /// (x,y) in \p Dependencies, both x and y must be in \p Changes. The
61  /// minimization algorithm guarantees that for each tested changed set S,
62  /// \f$ x \in S \f$ implies \f$ y \in S \f$. It is an error to have cyclic
63  /// dependencies.
64  changeset_ty Run(const changeset_ty &Changes,
65  const std::vector<edge_ty> &Dependencies);
66 
67  /// UpdatedSearchState - Callback used when the search state changes.
68  virtual void UpdatedSearchState(const changeset_ty &Changes,
69  const changesetlist_ty &Sets,
70  const changeset_ty &Required) {}
71 
72  /// ExecuteOneTest - Execute a single test predicate on the change set \p S.
73  virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
74 };
75 
76 } // end namespace llvm
77 
78 #endif // LLVM_ADT_DAGDELTAALGORITHM_H
DAGDeltaAlgorithm - Implements a "delta debugging" algorithm for minimizing directed acyclic graphs u...
This class represents lattice values for constants.
Definition: AllocatorList.h:23
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.