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 <vector> 13 #include <set> 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. 38 class DAGDeltaAlgorithm { 39 public: 40 typedef unsigned change_ty; 41 typedef std::pair<change_ty, change_ty> edge_ty; 42 43 // FIXME: Use a decent data structure. 44 typedef std::set<change_ty> changeset_ty; 45 typedef std::vector<changeset_ty> changesetlist_ty; 46 47 public: 48 virtual ~DAGDeltaAlgorithm() {} 49 50 /// Run - Minimize the DAG formed by the \arg Changes vertices and the \arg 51 /// Dependencies edges by executing \see ExecuteOneTest() on subsets of 52 /// changes and returning the smallest set which still satisfies the test 53 /// predicate and the input \arg Dependencies. 54 /// 55 /// \param Changes The list of changes. 56 /// 57 /// \param Dependencies The list of dependencies amongst changes. For each 58 /// (x,y) in \arg Dependencies, both x and y must be in \arg Changes. The 59 /// minimization algorithm guarantees that for each tested changed set S, x 60 /// \in S implies y \in S. It is an error to have cyclic dependencies. 61 changeset_ty Run(const changeset_ty &Changes, 62 const std::vector<edge_ty> &Dependencies); 63 64 /// UpdatedSearchState - Callback used when the search state changes. 65 virtual void UpdatedSearchState(const changeset_ty &Changes, 66 const changesetlist_ty &Sets, 67 const changeset_ty &Required) {} 68 69 /// ExecuteOneTest - Execute a single test predicate on the change set \arg S. 70 virtual bool ExecuteOneTest(const changeset_ty &S) = 0; 71 }; 72 73 } // end namespace llvm 74 75 #endif 76
