1 //===--- DAGDeltaAlgorithm.h - A DAG Minimization Algorithm ----*- C++ -*--===//
3 // The LLVM Compiler Infrastructure
5 // This file is distributed under the University of Illinois Open Source
6 // License. See LICENSE.TXT for details.
7 //===----------------------------------------------------------------------===//
9 #ifndef LLVM_ADT_DAGDELTAALGORITHM_H
10 #define LLVM_ADT_DAGDELTAALGORITHM_H
17 /// DAGDeltaAlgorithm - Implements a "delta debugging" algorithm for minimizing
18 /// directed acyclic graphs using a predicate function.
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.
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:
30 /// P(S) => P(S union pred(S))
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
38 class DAGDeltaAlgorithm {
40 typedef unsigned change_ty;
41 typedef std::pair<change_ty, change_ty> edge_ty;
43 // FIXME: Use a decent data structure.
44 typedef std::set<change_ty> changeset_ty;
45 typedef std::vector<changeset_ty> changesetlist_ty;
48 /// Run - Minimize the DAG formed by the \arg Changes vertices and the \arg
49 /// Dependencies edges by executing \see ExecuteOneTest() on subsets of
50 /// changes and returning the smallest set which still satisfies the test
51 /// predicate and the input \arg Dependencies.
53 /// \param Changes The list of changes.
55 /// \param Dependencies The list of dependencies amongst changes. For each
56 /// (x,y) in \arg Dependencies, both x and y must be in \arg Changes. The
57 /// minimization algorithm guarantees that for each tested changed set S, x
58 /// \in S implies y \in S. It is an error to have cyclic dependencies.
59 changeset_ty Run(const changeset_ty &Changes,
60 const std::vector<edge_ty> &Dependencies);
62 /// UpdatedSearchState - Callback used when the search state changes.
63 virtual void UpdatedSearchState(const changeset_ty &Changes,
64 const changesetlist_ty &Sets,
65 const changeset_ty &Required) {}
67 /// ExecuteOneTest - Execute a single test predicate on the change set \arg S.
68 virtual bool ExecuteOneTest(const changeset_ty &S) = 0;
71 } // end namespace llvm