1 /********************* */
2 /*! \file theory_engine.h
4 ** Top contributors (to current version):
5 ** Dejan Jovanovic, Andrew Reynolds, Morgan Deters
6 ** This file is part of the CVC4 project.
7 ** Copyright (c) 2009-2020 by the authors listed in the file AUTHORS
8 ** in the top-level source directory) and their institutional affiliations.
9 ** All rights reserved. See the file COPYING in the top-level source
10 ** directory for licensing information.\endverbatim
12 ** \brief The theory engine
17 #include "cvc4_private.h"
19 #ifndef CVC4__THEORY_ENGINE_H
20 #define CVC4__THEORY_ENGINE_H
25 #include <unordered_map>
29 #include "base/check.h"
30 #include "context/cdhashset.h"
31 #include "expr/node.h"
32 #include "options/options.h"
33 #include "options/smt_options.h"
34 #include "options/theory_options.h"
35 #include "prop/prop_engine.h"
36 #include "smt/command.h"
37 #include "theory/atom_requests.h"
38 #include "theory/decision_manager.h"
39 #include "theory/engine_output_channel.h"
40 #include "theory/interrupted.h"
41 #include "theory/rewriter.h"
42 #include "theory/shared_terms_database.h"
43 #include "theory/sort_inference.h"
44 #include "theory/substitutions.h"
45 #include "theory/term_registration_visitor.h"
46 #include "theory/theory.h"
47 #include "theory/theory_preprocessor.h"
48 #include "theory/uf/equality_engine.h"
49 #include "theory/valuation.h"
50 #include "util/hash.h"
51 #include "util/resource_manager.h"
52 #include "util/statistics_registry.h"
53 #include "util/unsafe_interrupt_exception.h"
57 class ResourceManager
;
58 class LemmaProofRecipe
;
61 * A pair of a theory and a node. This is used to mark the flow of
62 * propagations between theories.
64 struct NodeTheoryPair
{
66 theory::TheoryId d_theory
;
68 NodeTheoryPair(TNode n
, theory::TheoryId t
, size_t ts
= 0)
69 : d_node(n
), d_theory(t
), d_timestamp(ts
)
72 NodeTheoryPair() : d_theory(theory::THEORY_LAST
), d_timestamp() {}
73 // Comparison doesn't take into account the timestamp
74 bool operator == (const NodeTheoryPair
& pair
) const {
75 return d_node
== pair
.d_node
&& d_theory
== pair
.d_theory
;
77 };/* struct NodeTheoryPair */
79 struct NodeTheoryPairHashFunction
{
80 NodeHashFunction hashFunction
;
81 // Hash doesn't take into account the timestamp
82 size_t operator()(const NodeTheoryPair
& pair
) const {
83 uint64_t hash
= fnv1a::fnv1a_64(NodeHashFunction()(pair
.d_node
));
84 return static_cast<size_t>(fnv1a::fnv1a_64(pair
.d_theory
, hash
));
86 };/* struct NodeTheoryPairHashFunction */
89 /* Forward declarations */
92 class TheoryEngineModelBuilder
;
96 }/* CVC4::theory::eq namespace */
98 namespace quantifiers
{
102 class EntailmentCheckParameters
;
103 class EntailmentCheckSideEffects
;
104 }/* CVC4::theory namespace */
106 class RemoveTermFormulas
;
109 * This is essentially an abstraction for a collection of theories. A
110 * TheoryEngine provides services to a PropEngine, making various
111 * T-solvers look like a single unit to the propositional part of
116 /** Shared terms database can use the internals notify the theories */
117 friend class SharedTermsDatabase
;
118 friend class theory::quantifiers::TermDb
;
119 friend class theory::EngineOutputChannel
;
121 /** Associated PropEngine engine */
122 prop::PropEngine
* d_propEngine
;
125 context::Context
* d_context
;
127 /** Our user context */
128 context::UserContext
* d_userContext
;
131 * A table of from theory IDs to theory pointers. Never use this table
132 * directly, use theoryOf() instead.
134 theory::Theory
* d_theoryTable
[theory::THEORY_LAST
];
137 * A collection of theories that are "active" for the current run.
138 * This set is provided by the user (as a logic string, say, in SMT-LIBv2
139 * format input), or else by default it's all-inclusive. This is important
140 * because we can optimize for single-theory runs (no sharing), can reduce
141 * the cost of walking the DAG on registration, etc.
143 const LogicInfo
& d_logicInfo
;
146 * The database of shared terms.
148 SharedTermsDatabase d_sharedTerms
;
151 * Master equality engine, to share with theories.
153 theory::eq::EqualityEngine
* d_masterEqualityEngine
;
155 /** notify class for master equality engine */
156 class NotifyClass
: public theory::eq::EqualityEngineNotify
{
159 NotifyClass(TheoryEngine
& te
): d_te(te
) {}
160 bool eqNotifyTriggerEquality(TNode equality
, bool value
) override
164 bool eqNotifyTriggerPredicate(TNode predicate
, bool value
) override
168 bool eqNotifyTriggerTermEquality(theory::TheoryId tag
,
175 void eqNotifyConstantTermMerge(TNode t1
, TNode t2
) override
{}
176 void eqNotifyNewClass(TNode t
) override
{ d_te
.eqNotifyNewClass(t
); }
177 void eqNotifyPreMerge(TNode t1
, TNode t2
) override
180 void eqNotifyPostMerge(TNode t1
, TNode t2
) override
183 void eqNotifyDisequal(TNode t1
, TNode t2
, TNode reason
) override
186 };/* class TheoryEngine::NotifyClass */
187 NotifyClass d_masterEENotify
;
190 * notification methods
192 void eqNotifyNewClass(TNode t
);
193 void eqNotifyPreMerge(TNode t1
, TNode t2
);
194 void eqNotifyPostMerge(TNode t1
, TNode t2
);
195 void eqNotifyDisequal(TNode t1
, TNode t2
, TNode reason
);
198 * The quantifiers engine
200 theory::QuantifiersEngine
* d_quantEngine
;
202 * The decision manager
204 std::unique_ptr
<theory::DecisionManager
> d_decManager
;
207 * Default model object
209 theory::TheoryModel
* d_curr_model
;
210 bool d_aloc_curr_model
;
212 * Model builder object
214 theory::TheoryEngineModelBuilder
* d_curr_model_builder
;
215 bool d_aloc_curr_model_builder
;
216 /** are we in eager model building mode? (see setEagerModelBuilding). */
217 bool d_eager_model_building
;
219 typedef std::unordered_map
<Node
, Node
, NodeHashFunction
> NodeMap
;
220 typedef std::unordered_map
<TNode
, Node
, TNodeHashFunction
> TNodeMap
;
223 * Used for "missed-t-propagations" dumping mode only. A set of all
224 * theory-propagable literals.
226 context::CDList
<TNode
> d_possiblePropagations
;
229 * Used for "missed-t-propagations" dumping mode only. A
230 * context-dependent set of those theory-propagable literals that
231 * have been propagated.
233 context::CDHashSet
<Node
, NodeHashFunction
> d_hasPropagated
;
236 * Output channels for individual theories.
238 theory::EngineOutputChannel
* d_theoryOut
[theory::THEORY_LAST
];
241 * Are we in conflict.
243 context::CDO
<bool> d_inConflict
;
246 * Are we in "SAT mode"? In this state, the user can query for the model.
247 * This corresponds to the state in Figure 4.1, page 52 of the SMT-LIB
248 * standard, version 2.6.
253 * Called by the theories to notify of a conflict.
255 void conflict(TNode conflict
, theory::TheoryId theoryId
);
258 * Debugging flag to ensure that shutdown() is called before the
264 * True if a theory has notified us of incompleteness (at this
265 * context level or below).
267 context::CDO
<bool> d_incomplete
;
270 * Called by the theories to notify that the current branch is incomplete.
272 void setIncomplete(theory::TheoryId theory
) {
278 * Mapping of propagations from recievers to senders.
280 typedef context::CDHashMap
<NodeTheoryPair
, NodeTheoryPair
, NodeTheoryPairHashFunction
> PropagationMap
;
281 PropagationMap d_propagationMap
;
284 * Timestamp of propagations
286 context::CDO
<size_t> d_propagationMapTimestamp
;
289 * Literals that are propagated by the theory. Note that these are TNodes.
290 * The theory can only propagate nodes that have an assigned literal in the
291 * SAT solver and are hence referenced in the SAT solver.
293 context::CDList
<TNode
> d_propagatedLiterals
;
296 * The index of the next literal to be propagated by a theory.
298 context::CDO
<unsigned> d_propagatedLiteralsIndex
;
301 * Called by the output channel to propagate literals and facts
302 * @return false if immediate conflict
304 bool propagate(TNode literal
, theory::TheoryId theory
);
307 * Internal method to call the propagation routines and collect the
308 * propagated literals.
310 void propagate(theory::Theory::Effort effort
);
313 * A variable to mark if we added any lemmas.
318 * A variable to mark if the OutputChannel was "used" by any theory
319 * since the start of the last check. If it has been, we require
320 * a FULL_EFFORT check before exiting and reporting SAT.
322 * See the documentation for the needCheck() function, below.
324 bool d_outputChannelUsed
;
326 /** Atom requests from lemmas */
327 AtomRequests d_atomRequests
;
330 * Adds a new lemma, returning its status.
331 * @param node the lemma
332 * @param negated should the lemma be asserted negated
333 * @param removable can the lemma be remove (restrictions apply)
334 * @param needAtoms if not THEORY_LAST, then
336 theory::LemmaStatus
lemma(TNode node
,
341 theory::TheoryId atomsTo
);
343 /** Enusre that the given atoms are send to the given theory */
344 void ensureLemmaAtoms(const std::vector
<TNode
>& atoms
, theory::TheoryId theory
);
346 /** sort inference module */
347 SortInference d_sortInfer
;
349 /** The theory preprocessor */
350 theory::TheoryPreprocessor d_tpp
;
352 /** Time spent in theory combination */
353 TimerStat d_combineTheoriesTime
;
358 /** Whether we were just interrupted (or not) */
360 ResourceManager
* d_resourceManager
;
363 /** Constructs a theory engine */
364 TheoryEngine(context::Context
* context
,
365 context::UserContext
* userContext
,
366 RemoveTermFormulas
& iteRemover
,
367 const LogicInfo
& logic
);
369 /** Destroys a theory engine */
374 /** "Spend" a resource during a search or preprocessing.*/
375 void spendResource(ResourceManager::Resource r
);
378 * Adds a theory. Only one theory per TheoryId can be present, so if
379 * there is another theory it will be deleted.
381 template <class TheoryClass
>
382 inline void addTheory(theory::TheoryId theoryId
)
384 Assert(d_theoryTable
[theoryId
] == NULL
&& d_theoryOut
[theoryId
] == NULL
);
385 d_theoryOut
[theoryId
] = new theory::EngineOutputChannel(this, theoryId
);
386 d_theoryTable
[theoryId
] = new TheoryClass(d_context
,
388 *d_theoryOut
[theoryId
],
389 theory::Valuation(this),
391 theory::Rewriter::registerTheoryRewriter(
392 theoryId
, d_theoryTable
[theoryId
]->getTheoryRewriter());
395 void setPropEngine(prop::PropEngine
* propEngine
)
397 d_propEngine
= propEngine
;
400 /** Called when all initialization of options/logic is done */
404 * Get a pointer to the underlying propositional engine.
406 inline prop::PropEngine
* getPropEngine() const {
411 * Get a pointer to the underlying sat context.
413 inline context::Context
* getSatContext() const {
418 * Get a pointer to the underlying user context.
420 inline context::Context
* getUserContext() const {
421 return d_userContext
;
425 * Get a pointer to the underlying quantifiers engine.
427 theory::QuantifiersEngine
* getQuantifiersEngine() const {
428 return d_quantEngine
;
431 * Get a pointer to the underlying decision manager.
433 theory::DecisionManager
* getDecisionManager() const
435 return d_decManager
.get();
440 * Queue of nodes for pre-registration.
442 std::queue
<TNode
> d_preregisterQueue
;
445 * Boolean flag denoting we are in pre-registration.
447 bool d_inPreregister
;
450 * Did the theories get any new facts since the last time we called
453 context::CDO
<bool> d_factsAsserted
;
456 * Map from equality atoms to theories that would like to be notified about them.
461 * Assert the formula to the given theory.
462 * @param assertion the assertion to send (not necesserily normalized)
463 * @param original the assertion as it was sent in from the propagating theory
464 * @param toTheoryId the theory to assert to
465 * @param fromTheoryId the theory that sent it
467 void assertToTheory(TNode assertion
, TNode originalAssertion
, theory::TheoryId toTheoryId
, theory::TheoryId fromTheoryId
);
470 * Marks a theory propagation from a theory to a theory where a
471 * theory could be the THEORY_SAT_SOLVER for literals coming from
472 * or being propagated to the SAT solver. If the receiving theory
473 * already recieved the literal, the method returns false, otherwise
476 * @param assertion the normalized assertion being sent
477 * @param originalAssertion the actual assertion that was sent
478 * @param toTheoryId the theory that is on the receiving end
479 * @param fromTheoryId the theory that sent the assertion
480 * @return true if a new assertion, false if theory already got it
482 bool markPropagation(TNode assertion
, TNode originalAssertions
, theory::TheoryId toTheoryId
, theory::TheoryId fromTheoryId
);
485 * Computes the explanation by travarsing the propagation graph and
486 * asking relevant theories to explain the propagations. Initially
487 * the explanation vector should contain only the element (node, theory)
488 * where the node is the one to be explained, and the theory is the
489 * theory that sent the literal. The lemmaProofRecipe will contain a list
490 * of the explanation steps required to produce the original node.
492 void getExplanation(std::vector
<NodeTheoryPair
>& explanationVector
, LemmaProofRecipe
* lemmaProofRecipe
);
497 * Signal the start of a new round of assertion preprocessing
499 void preprocessStart();
502 * Runs theory specific preprocessing on the non-Boolean parts of
503 * the formula. This is only called on input assertions, after ITEs
506 Node
preprocess(TNode node
);
508 /** Notify (preprocessed) assertions. */
509 void notifyPreprocessedAssertions(const std::vector
<Node
>& assertions
);
511 /** Return whether or not we are incomplete (in the current context). */
512 inline bool isIncomplete() const { return d_incomplete
; }
515 * Returns true if we need another round of checking. If this
516 * returns true, check(FULL_EFFORT) _must_ be called by the
517 * propositional layer before reporting SAT.
519 * This is especially necessary for incomplete theories that lazily
520 * output some lemmas on FULL_EFFORT check (e.g. quantifier reasoning
521 * outputing quantifier instantiations). In such a case, a lemma can
522 * be asserted that is simplified away (perhaps it's already true).
523 * However, we must maintain the invariant that, if a theory uses the
524 * OutputChannel, it implicitly requests that another check(FULL_EFFORT)
525 * be performed before exit, even if no new facts are on its fact queue,
526 * as it might decide to further instantiate some lemmas, precluding
529 inline bool needCheck() const {
530 return d_outputChannelUsed
|| d_lemmasAdded
;
534 * This is called at shutdown time by the SmtEngine, just before
535 * destruction. It is important because there are destruction
536 * ordering issues between PropEngine and Theory.
541 * Solve the given literal with a theory that owns it.
543 theory::Theory::PPAssertStatus
solve(TNode literal
,
544 theory::SubstitutionMap
& substitutionOut
);
547 * Preregister a Theory atom with the responsible theory (or
550 void preRegister(TNode preprocessed
);
553 * Assert the formula to the appropriate theory.
554 * @param node the assertion
556 void assertFact(TNode node
);
559 * Check all (currently-active) theories for conflicts.
560 * @param effort the effort level to use
562 void check(theory::Theory::Effort effort
);
565 * Run the combination framework.
567 void combineTheories();
570 * Calls ppStaticLearn() on all theories, accumulating their
571 * combined contributions in the "learned" builder.
573 void ppStaticLearn(TNode in
, NodeBuilder
<>& learned
);
576 * Calls presolve() on all theories and returns true
577 * if one of the theories discovers a conflict.
582 * Calls postsolve() on all theories.
587 * Calls notifyRestart() on all active theories.
589 void notifyRestart();
591 void getPropagatedLiterals(std::vector
<TNode
>& literals
) {
592 for (; d_propagatedLiteralsIndex
< d_propagatedLiterals
.size(); d_propagatedLiteralsIndex
= d_propagatedLiteralsIndex
+ 1) {
593 Debug("getPropagatedLiterals") << "TheoryEngine::getPropagatedLiterals: propagating: " << d_propagatedLiterals
[d_propagatedLiteralsIndex
] << std::endl
;
594 literals
.push_back(d_propagatedLiterals
[d_propagatedLiteralsIndex
]);
599 * Returns the next decision request, or null if none exist. The next
600 * decision request is a literal that this theory engine prefers the SAT
601 * solver to make as its next decision. Decision requests are managed by
602 * the decision manager d_decManager.
604 Node
getNextDecisionRequest();
606 bool properConflict(TNode conflict
) const;
607 bool properPropagation(TNode lit
) const;
608 bool properExplanation(TNode node
, TNode expl
) const;
611 * Returns an explanation of the node propagated to the SAT solver.
613 Node
getExplanation(TNode node
);
616 * Returns an explanation of the node propagated to the SAT solver and the theory
617 * that propagated it.
619 Node
getExplanationAndRecipe(TNode node
, LemmaProofRecipe
* proofRecipe
);
624 bool collectModelInfo(theory::TheoryModel
* m
);
625 /** post process model */
626 void postProcessModel( theory::TheoryModel
* m
);
629 * Get the pointer to the model object used by this theory engine.
631 theory::TheoryModel
* getModel();
633 * Get the current model for the current set of assertions. This method
634 * should only be called immediately after a satisfiable or unknown
635 * response to a check-sat call, and only if produceModels is true.
637 * If the model is not already built, this will cause this theory engine
638 * to build the model.
640 * If the model is not available (for instance, if the last call to check-sat
641 * was interrupted), then this returns the null pointer.
643 theory::TheoryModel
* getBuiltModel();
644 /** set eager model building
646 * If this method is called, then this TheoryEngine will henceforth build
647 * its model immediately after every satisfiability check that results
648 * in a satisfiable or unknown result. The motivation for this mode is to
649 * accomodate API users that get the model object from the TheoryEngine,
650 * where we want to ensure that this model is always valid.
651 * TODO (#2648): revisit this.
653 void setEagerModelBuilding() { d_eager_model_building
= true; }
655 /** get synth solutions
657 * This method returns true if there is a synthesis solution available. This
658 * is the case if the last call to check satisfiability originated in a
659 * check-synth call, and the synthesis solver successfully found a solution
660 * for all active synthesis conjectures.
662 * This method adds entries to sol_map that map functions-to-synthesize with
663 * their solutions, for all active conjectures. This should be called
664 * immediately after the solver answers unsat for sygus input.
666 * For details on what is added to sol_map, see
667 * SynthConjecture::getSynthSolutions.
669 bool getSynthSolutions(std::map
<Node
, std::map
<Node
, Node
> >& sol_map
);
672 * Get the model builder
674 theory::TheoryEngineModelBuilder
* getModelBuilder() { return d_curr_model_builder
; }
677 * Get the theory associated to a given Node.
679 * @returns the theory, or NULL if the TNode is
682 inline theory::Theory
* theoryOf(TNode node
) const {
683 return d_theoryTable
[theory::Theory::theoryOf(node
)];
687 * Get the theory associated to a the given theory id.
689 * @returns the theory
691 inline theory::Theory
* theoryOf(theory::TheoryId theoryId
) const {
692 Assert(theoryId
< theory::THEORY_LAST
);
693 return d_theoryTable
[theoryId
];
696 inline bool isTheoryEnabled(theory::TheoryId theoryId
) const {
697 return d_logicInfo
.isTheoryEnabled(theoryId
);
699 /** get the logic info used by this theory engine */
700 const LogicInfo
& getLogicInfo() const;
702 * Returns the equality status of the two terms, from the theory
703 * that owns the domain type. The types of a and b must be the same.
705 theory::EqualityStatus
getEqualityStatus(TNode a
, TNode b
);
708 * Returns the value that a theory that owns the type of var currently
709 * has (or null if none);
711 Node
getModelValue(TNode var
);
714 * Takes a literal and returns an equivalent literal that is guaranteed to be a SAT literal
716 Node
ensureLiteral(TNode n
);
719 * Print all instantiations made by the quantifiers module.
721 void printInstantiations( std::ostream
& out
);
724 * Print solution for synthesis conjectures found by ce_guided_instantiation module
726 void printSynthSolution( std::ostream
& out
);
729 * Get list of quantified formulas that were instantiated
731 void getInstantiatedQuantifiedFormulas( std::vector
< Node
>& qs
);
734 * Get instantiation methods
735 * first inputs forall x.q[x] and returns ( q[a], ..., q[z] )
736 * second inputs forall x.q[x] and returns ( a, ..., z )
737 * third and fourth return mappings e.g. forall x.q1[x] -> ( q1[a]...q1[z] ) , ... , forall x.qn[x] -> ( qn[a]...qn[z] )
739 void getInstantiations( Node q
, std::vector
< Node
>& insts
);
740 void getInstantiationTermVectors( Node q
, std::vector
< std::vector
< Node
> >& tvecs
);
741 void getInstantiations( std::map
< Node
, std::vector
< Node
> >& insts
);
742 void getInstantiationTermVectors( std::map
< Node
, std::vector
< std::vector
< Node
> > >& insts
);
745 * Get instantiated conjunction, returns q[t1] ^ ... ^ q[tn] where t1...tn are current set of instantiations for q.
746 * Can be used for quantifier elimination when satisfiable and q[t1] ^ ... ^ q[tn] |= q
748 Node
getInstantiatedConjunction( Node q
);
751 * Forwards an entailment check according to the given theoryOfMode.
752 * See theory.h for documentation on entailmentCheck().
754 std::pair
<bool, Node
> entailmentCheck(
755 options::TheoryOfMode mode
,
757 const theory::EntailmentCheckParameters
* params
= NULL
,
758 theory::EntailmentCheckSideEffects
* out
= NULL
);
761 /** Default visitor for pre-registration */
762 PreRegisterVisitor d_preRegistrationVisitor
;
764 /** Visitor for collecting shared terms */
765 SharedTermsVisitor d_sharedTermsVisitor
;
767 /** Dump the assertions to the dump */
768 void dumpAssertions(const char* tag
);
770 /** For preprocessing pass lifting bit-vectors of size 1 to booleans */
772 void staticInitializeBVOptions(const std::vector
<Node
>& assertions
);
774 Node
ppSimpITE(TNode assertion
);
775 /** Returns false if an assertion simplified to false. */
776 bool donePPSimpITE(std::vector
<Node
>& assertions
);
778 SharedTermsDatabase
* getSharedTermsDatabase() { return &d_sharedTerms
; }
780 theory::eq::EqualityEngine
* getMasterEqualityEngine() { return d_masterEqualityEngine
; }
782 SortInference
* getSortInference() { return &d_sortInfer
; }
784 /** Prints the assertions to the debug stream */
785 void printAssertions(const char* tag
);
789 std::map
< std::string
, std::vector
< theory::Theory
* > > d_attr_handle
;
792 /** Set user attribute.
794 * This function is called when an attribute is set by a user. In SMT-LIBv2
795 * this is done via the syntax (! n :attr)
797 void setUserAttribute(const std::string
& attr
,
799 const std::vector
<Node
>& node_values
,
800 const std::string
& str_value
);
802 /** Handle user attribute.
804 * Associates theory t with the attribute attr. Theory t will be
805 * notified whenever an attribute of name attr is set.
807 void handleUserAttribute(const char* attr
, theory::Theory
* t
);
810 * Check that the theory assertions are satisfied in the model.
811 * This function is called from the smt engine's checkModel routine.
813 void checkTheoryAssertionsWithModel(bool hardFailure
);
816 IntStat d_arithSubstitutionsAdded
;
818 };/* class TheoryEngine */
820 }/* CVC4 namespace */
822 #endif /* CVC4__THEORY_ENGINE_H */