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. 39 class DAGDeltaAlgorithm { 40 virtual void anchor(); 41 42 public: 43 using change_ty = unsigned; 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 80
