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z3/src/sat/smt/array_solver.h
2021-03-13 06:19:32 -08:00

232 lines
9.9 KiB
C++

/*++
Copyright (c) 2020 Microsoft Corporation
Module Name:
array_solver.h
Abstract:
Theory plugin for arrays
Author:
Nikolaj Bjorner (nbjorner) 2020-09-08
--*/
#pragma once
#include "ast/ast_trail.h"
#include "sat/smt/sat_th.h"
#include "ast/array_decl_plugin.h"
namespace euf {
class solver;
}
namespace array {
class solver : public euf::th_euf_solver {
typedef euf::theory_var theory_var;
typedef euf::theory_id theory_id;
typedef sat::literal literal;
typedef sat::bool_var bool_var;
typedef sat::literal_vector literal_vector;
typedef union_find<solver, euf::solver> array_union_find;
struct stats {
unsigned m_num_store_axiom, m_num_extensionality_axiom;
unsigned m_num_eq_splits, m_num_congruence_axiom;
unsigned m_num_select_store_axiom, m_num_select_as_array_axiom, m_num_select_map_axiom;
unsigned m_num_select_const_axiom, m_num_select_store_axiom_delayed;
unsigned m_num_default_store_axiom, m_num_default_map_axiom;
unsigned m_num_default_const_axiom, m_num_default_as_array_axiom;
unsigned m_num_select_lambda_axiom;
void reset() { memset(this, 0, sizeof(*this)); }
stats() { reset(); }
};
// void log_drat(array_justification const& c);
struct var_data {
bool m_prop_upward{ false };
euf::enode_vector m_lambdas; // equivalent nodes that have beta reduction properties
euf::enode_vector m_parent_lambdas; // parents that have beta reduction properties
euf::enode_vector m_parent_selects; // parents that use array in select position
var_data() {}
};
array_util a;
stats m_stats;
scoped_ptr_vector<var_data> m_var_data;
ast2ast_trailmap<sort, app> m_sort2epsilon;
ast2ast_trailmap<sort, func_decl> m_sort2diag;
obj_map<sort, func_decl_ref_vector*> m_sort2diff;
array_union_find m_find;
theory_var find(theory_var v) { return m_find.find(v); }
func_decl_ref_vector const& sort2diff(sort* s);
// internalize
bool visit(expr* e) override;
bool visited(expr* e) override;
bool post_visit(expr* e, bool sign, bool root) override;
void ensure_var(euf::enode* n);
void internalize_store(euf::enode* n);
void internalize_select(euf::enode* n);
void internalize_lambda(euf::enode* n);
void internalize_ext(euf::enode* n);
void internalize_default(euf::enode* n);
void internalize_map(euf::enode* n);
// axioms
struct axiom_record {
enum class kind_t {
is_store,
is_select,
is_extensionality,
is_default,
is_congruence
};
kind_t m_kind;
euf::enode* n;
euf::enode* select;
bool m_delayed { false };
axiom_record(kind_t k, euf::enode* n, euf::enode* select = nullptr) : m_kind(k), n(n), select(select) {}
bool is_delayed() const { return m_delayed; }
struct hash {
solver& s;
hash(solver& s) :s(s) {}
unsigned operator()(unsigned idx) const {
auto const& r = s.m_axiom_trail[idx];
return mk_mix(r.n->get_expr_id(), (unsigned)r.m_kind, r.select ? r.select->get_expr_id() : 1);
}
};
struct eq {
solver& s;
eq(solver& s) :s(s) {}
unsigned operator()(unsigned a, unsigned b) const {
auto const& p = s.m_axiom_trail[a];
auto const& r = s.m_axiom_trail[b];
return p.n == r.n && p.select == r.select && p.m_kind == r.m_kind;
}
};
};
typedef hashtable<unsigned, axiom_record::hash, axiom_record::eq> axiom_table_t;
axiom_record::hash m_hash;
axiom_record::eq m_eq;
axiom_table_t m_axioms;
svector<axiom_record> m_axiom_trail;
unsigned m_qhead { 0 };
unsigned m_delay_qhead { 0 };
bool m_enable_delay { true };
struct set_delay_bit;
void push_axiom(axiom_record const& r);
bool propagate_axiom(unsigned idx);
bool assert_axiom(unsigned idx);
bool assert_select(unsigned idx, axiom_record & r);
bool assert_default(axiom_record & r);
bool is_relevant(axiom_record const& r) const;
axiom_record select_axiom(euf::enode* s, euf::enode* n) { return axiom_record(axiom_record::kind_t::is_select, n, s); }
axiom_record default_axiom(euf::enode* n) { return axiom_record(axiom_record::kind_t::is_default, n); }
axiom_record store_axiom(euf::enode* n) { return axiom_record(axiom_record::kind_t::is_store, n); }
axiom_record extensionality_axiom(euf::enode* x, euf::enode* y) { return axiom_record(axiom_record::kind_t::is_extensionality, x, y); }
axiom_record congruence_axiom(euf::enode* a, euf::enode* b) { return axiom_record(axiom_record::kind_t::is_congruence, a, b); }
scoped_ptr<sat::constraint_base> m_constraint;
sat::ext_justification_idx array_axiom() { return m_constraint->to_index(); }
bool assert_store_axiom(app* _e);
bool assert_select_store_axiom(app* select, app* store);
bool assert_select_const_axiom(app* select, app* cnst);
bool assert_select_as_array_axiom(app* select, app* arr);
bool assert_select_map_axiom(app* select, app* map);
bool assert_select_lambda_axiom(app* select, expr* lambda);
bool assert_extensionality(expr* e1, expr* e2);
bool assert_default_map_axiom(app* map);
bool assert_default_const_axiom(app* cnst);
bool assert_default_store_axiom(app* store);
bool assert_congruent_axiom(expr* e1, expr* e2);
bool add_delayed_axioms();
bool has_unitary_domain(app* array_term);
bool has_large_domain(expr* array_term);
std::pair<app*, func_decl*> mk_epsilon(sort* s);
void collect_shared_vars(sbuffer<theory_var>& roots);
bool add_interface_equalities();
bool is_select_arg(euf::enode* r);
bool is_array(euf::enode* n) const { return a.is_array(n->get_expr()); }
// solving
void add_parent_select(theory_var v_child, euf::enode* select);
void add_parent_default(theory_var v_child, euf::enode* def);
void add_lambda(theory_var v, euf::enode* lambda);
void add_parent_lambda(theory_var v_child, euf::enode* lambda);
void propagate_select_axioms(var_data const& d, euf::enode* a);
void propagate_parent_select_axioms(theory_var v);
void propagate_parent_default(theory_var v);
void set_prop_upward(theory_var v);
void set_prop_upward(var_data& d);
void set_prop_upward(euf::enode* n);
unsigned get_lambda_equiv_size(var_data const& d) const;
bool should_set_prop_upward(var_data const& d) const;
bool should_prop_upward(var_data const& d) const;
bool can_beta_reduce(euf::enode* n) const;
var_data& get_var_data(euf::enode* n) { return get_var_data(n->get_th_var(get_id())); }
var_data& get_var_data(theory_var v) { return *m_var_data[v]; }
var_data const& get_var_data(theory_var v) const { return *m_var_data[v]; }
void pop_core(unsigned n) override;
// models
bool have_different_model_values(theory_var v1, theory_var v2);
// diagnostics
std::ostream& display_info(std::ostream& out, char const* id, euf::enode_vector const& v) const;
std::ostream& display(std::ostream& out, axiom_record const& r) const;
void validate_check() const;
void validate_select_store(euf::enode* n) const;
void validate_extensionality(euf::enode* s, euf::enode* t) const;
public:
solver(euf::solver& ctx, theory_id id);
~solver() override;
bool is_external(bool_var v) override { return false; }
void get_antecedents(literal l, sat::ext_justification_idx idx, literal_vector& r, bool probing) override {}
void asserted(literal l) override {}
sat::check_result check() override;
std::ostream& display(std::ostream& out) const override;
std::ostream& display_justification(std::ostream& out, sat::ext_justification_idx idx) const override;
std::ostream& display_constraint(std::ostream& out, sat::ext_constraint_idx idx) const override;
void collect_statistics(statistics& st) const override;
euf::th_solver* clone(euf::solver& ctx) override;
void new_eq_eh(euf::th_eq const& eq) override;
bool use_diseqs() const override { return true; }
void new_diseq_eh(euf::th_eq const& eq) override;
bool unit_propagate() override;
void add_value(euf::enode* n, model& mdl, expr_ref_vector& values) override;
bool add_dep(euf::enode* n, top_sort<euf::enode>& dep) override;
sat::literal internalize(expr* e, bool sign, bool root, bool learned) override;
void internalize(expr* e, bool redundant) override;
euf::theory_var mk_var(euf::enode* n) override;
void apply_sort_cnstr(euf::enode* n, sort* s) override;
bool is_shared(theory_var v) const override;
void merge_eh(theory_var, theory_var, theory_var v1, theory_var v2);
void after_merge_eh(theory_var r1, theory_var r2, theory_var v1, theory_var v2) {}
void unmerge_eh(theory_var v1, theory_var v2) {}
euf::enode_vector const& parent_selects(euf::enode* n) const { return m_var_data[n->get_th_var(get_id())]->m_parent_selects; }
};
}