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smtfd solver that uses lazy iteration around fd to produce theory lemmas

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-09-07 17:48:18 +03:00
parent e881c4af3f
commit c476c4a86a
4 changed files with 1029 additions and 0 deletions
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4
src/ast/rewriter/bv_rewriter.cpp
View file

@ -2244,6 +2244,10 @@ br_status bv_rewriter::mk_bv_mul(unsigned num_args, expr * const * args, expr_re
br_status bv_rewriter::mk_bit2bool(expr * n, int idx, expr_ref & result) {
rational v, bit;
unsigned sz = 0;
if (m_util.is_mkbv(n)) {
result = to_app(n)->get_arg(idx);
return BR_DONE;
}
if (!is_numeral(n, v, sz))
return BR_FAILED;
if (idx < 0 || idx >= static_cast<int>(sz))

2
src/tactic/fd_solver/CMakeLists.txt
View file

@ -4,8 +4,10 @@ z3_add_component(fd_solver
enum2bv_solver.cpp
fd_solver.cpp
pb2bv_solver.cpp
smtfd_solver.cpp
COMPONENT_DEPENDENCIES
sat_solver
TACTIC_HEADERS
fd_solver.h
smtfd_solver.h
)

988
src/tactic/fd_solver/smtfd_solver.cpp Normal file
View file

@ -0,0 +1,988 @@
/**
F1, F2, .., -> Fa1, Fa2, ...
assert incrementally:
t1 <-> Fa1
t2 <-> Fa2 & t1
....
abstraction replaces subterms that are not bv constants
by atomic formulas or a term of the form:
xor(random_bv, fresh_bv_variable) of enough (24) bits
Then default assignment to the fresh bv variable (to 0)
is hashed to a value that is likely different form other variables
of the same type, so two variables of the same type are then most
likely equal in a model if they have to be.
atoms := list of atomic formulas (including equalities over bit-vectors)
while True:
r = check_sat([t_k])
if r != sat:
return r
M = current model
literals := evaluation of atoms under M
r = check_sat([!t_k] + literals)
if r != unsat:
return unknown
core = rep(some unsat_core excluding !t_k)
if core is SAT modulo A + UF + other theories:
return SAT
optionally apply a step of superposition (reduce congruence and equality diamonds):
let t1 = t2, core1 := core, where t1 in core1
- t1 is uninterpreted constant
core := replace t1 by t2 in core1
- t1 = f(args):
core := replace all occurrences of t1' by t2 in core1 where M(abs(t1)) = M(abs(t1')).
- t1 = select(A,args)?
when is it safe to reduce t1?
for t in subterms(core) where t is f(args):
v1 := M(abs(t))
v_args = M(abs(args))
v2, t2 := table[f][v_args]
if v2 != null and v1 != v2:
lemmas += (args = t2.args => t = t2)
else:
table[f][v_args] := v1, t
for t in subterms(core) where t is select(A, args):
vA := M(abs(A))
v_args = M(abs(args))
v2, args2, t2 := table[vA][v_args]
if v2 != null and v1 != v2:
lemmas += (args1 = args2 => t = t2)
else:
table[vA][v_args] := v1, args, t
for t in subterms(core) where t is store(A, args, b):
vT := M(abs(t))
vA := M(abs(A))
vB := M(abs(b))
v2, args2, t2 := table[vT][v_args]
if v2 != null and vB != v2:
lemmas += (select(t, args) = b)
if v2 = null:
table[vT][v_args] := vB, args, t
for v_args2 |-> v2, args2, t2 in table[vA]:
check table[vT][v_args2] for compatibility with v2
if not compatible:
lemmas += (args2 != args => select(t, args2) = select(A, args2))
for v_args2 |-> v2, args2, t2 in table[tA]:
check table[vA][v_args2] for compatibility with v2
if not compatible:
lemmas += (args2 != args => select(t, args2) = select(A, args2))
for t in subterms(core) where t is const(k):
vk := M(abs(k))
vT := M(abs(t))
for v_args2 |-> v2, args2, t2 in table[vT]:
if vk != v2:
lemmas += (t = t2 => select(t2, args2) = k)
or lemmas += (select(t, args2) = k)
for t in subterms(core) where t is (lambda x . M), t is ground:
vT := M(abs(t))
for v_args2 |-> v2, args2, t2 in table[vT]:
v1 := M(abs(M[args2/x]))
if v1 != v2:
lemmas += (t = t2 => select(t2, args2) = M[args2/x])
for t in subterms(core) where t is map(f, A, B, C):
similar to lambda
for A in array_terms(core):
// extensionality:
vA := M(abs(A))
B := table[vA].array
if B = nil:
table[vA].array := A
else:
// add if not already true:
lemmas += (select(A, delta(A,B)) = select(B, delta(A,B)) => A = B)
if AUF solver timed out and lemmas == []:
really call AUF solver on core
return sat or continue with adding !core
add abs(!core) to solver
add abs(lemmas) to solver
*/
#include "util/scoped_ptr_vector.h"
#include "ast/ast_util.h"
#include "ast/ast_pp.h"
#include "ast/for_each_expr.h"
#include "ast/rewriter/th_rewriter.h"
#include "tactic/tactic_exception.h"
#include "tactic/fd_solver/fd_solver.h"
#include "solver/solver.h"
#include "solver/solver_na2as.h"
#include "solver/solver2tactic.h"
#include "smt/smt_solver.h"
namespace smtfd {
class smtfd_abs {
ast_manager& m;
expr_ref_vector m_abs, m_rep, m_atoms, m_atom_defs; // abstraction and representation maps
array_util m_autil;
bv_util m_butil;
ptr_vector<expr> m_args, m_todo;
unsigned m_nv;
unsigned_vector m_abs_trail, m_rep_trail, m_nv_trail;
unsigned_vector m_abs_lim, m_rep_lim, m_atoms_lim;
random_gen m_rand;
void pop(unsigned n, expr_ref_vector& v, unsigned_vector& trail, unsigned_vector& lim) {
SASSERT(n > 0);
unsigned sz = lim[lim.size() - n];
for (unsigned i = trail.size(); i-- > sz;) {
v[trail[i]] = nullptr;
}
trail.shrink(sz);
lim.shrink(lim.size() - n);
}
expr* try_abs(expr* e) { return m_abs.get(e->get_id(), nullptr); }
expr* try_rep(expr* e) { return m_rep.get(e->get_id(), nullptr); }
expr* fresh_var(expr* t) {
symbol name = is_app(t) ? to_app(t)->get_name() : symbol("X");
if (m.is_bool(t)) {
return m.mk_fresh_const(name, m.mk_bool_sort());
}
else if (m_butil.is_bv(t)) {
return m.mk_fresh_const(name, m.get_sort(t));
}
else {
++m_nv;
unsigned bw = log2(m_nv) + 1;
if (bw >= 24) {
throw default_exception("number of allowed bits for variables exceeded");
}
unsigned n = (m_rand() << 16) | m_rand();
expr* num = m_butil.mk_numeral(n, bw);
expr* es[2] = { num, m.mk_fresh_const(name, m_butil.mk_sort(bw)) };
expr* e = m_butil.mk_bv_xor(2, es);
return m_butil.mk_concat(e, m_butil.mk_numeral(0, 24 - bw));
}
}
void push_trail(expr_ref_vector& map, unsigned_vector& trail, expr* t, expr* r) {
unsigned idx = t->get_id();
map.reserve(idx + 1);
map.set(idx, r);
trail.push_back(idx);
}
bool is_atom(expr* r) {
if (!m.is_bool(r)) {
return false;
}
if (m.is_eq(r) && !m.is_bool(to_app(r)->get_arg(0))) {
return true;
}
return !is_app(r) || to_app(r)->get_family_id() != m.get_basic_family_id();
}
public:
smtfd_abs(ast_manager& m):
m(m),
m_abs(m),
m_rep(m),
m_atoms(m),
m_atom_defs(m),
m_autil(m),
m_butil(m),
m_nv(0)
{
abs(m.mk_true());
abs(m.mk_false());
}
expr_ref_vector const& atoms() {
return m_atoms;
}
expr_ref_vector const& atom_defs() {
return m_atom_defs;
}
void reset_atom_defs() {
m_atom_defs.reset();
}
void push() {
m_abs_lim.push_back(m_abs_trail.size());
m_rep_lim.push_back(m_rep_trail.size());
m_atoms_lim.push_back(m_atoms.size());
m_nv_trail.push_back(m_nv);
}
void pop(unsigned n) {
pop(n, m_abs, m_abs_trail, m_abs_lim);
pop(n, m_rep, m_rep_trail, m_rep_lim);
m_atoms.shrink(m_atoms_lim[m_atoms_lim.size() - n]);
m_atoms_lim.shrink(m_atoms_lim.size() - n);
m_nv = m_nv_trail[m_nv_trail.size() - n];
m_nv_trail.shrink(m_nv_trail.size() - n);
}
std::ostream& display(std::ostream& out) {
return out << "abs:\n" << m_atoms << "\n";
}
expr* abs(expr* e) {
expr* r = try_abs(e);
if (r) return r;
m_todo.push_back(e);
family_id bvfid = m_butil.get_fid();
family_id bfid = m.get_basic_family_id();
while (!m_todo.empty()) {
expr* t = m_todo.back();
r = try_abs(t);
if (r) {
m_todo.pop_back();
continue;
}
if (is_app(t)) {
app* a = to_app(t);
m_args.reset();
for (expr* arg : *a) {
r = try_abs(arg);
if (r) {
m_args.push_back(r);
}
else {
m_todo.push_back(arg);
}
}
if (m_args.size() != a->get_num_args()) {
continue;
}
family_id fid = a->get_family_id();
if (m.is_eq(a)) {
r = m.mk_eq(m_args.get(0), m_args.get(1));
}
else if (bvfid == fid || bfid == fid) {
r = m.mk_app(a->get_decl(), m_args.size(), m_args.c_ptr());
}
else if (is_uninterp_const(t) && m.is_bool(t)) {
r = t;
}
else if (is_uninterp_const(t) && m_butil.is_bv(t)) {
r = t;
}
else {
r = fresh_var(t);
}
}
else {
r = fresh_var(t);
}
if (is_atom(r) && !is_uninterp_const(r)) {
expr* rr = fresh_var(r);
m_atom_defs.push_back(m.mk_iff(rr, r));
r = rr;
}
push_trail(m_abs, m_abs_trail, t, r);
push_trail(m_rep, m_rep_trail, r, t);
if (is_atom(r)) {
m_atoms.push_back(r);
}
}
return try_abs(e);
}
expr* rep(expr* e) {
expr* r = try_rep(e);
if (r) return r;
VERIFY(m.is_not(e, r));
r = m.mk_not(try_rep(r));
abs(r);
return r;
}
};
struct f_app {
ast* m_f;
app* m_t;
unsigned m_val_offset;
};
class theory_plugin;
struct f_app_eq {
theory_plugin& p;
f_app_eq(theory_plugin& p):p(p) {}
bool operator()(f_app const& a, f_app const& b) const;
};
struct f_app_hash {
theory_plugin& p;
f_app_hash(theory_plugin& p):p(p) {}
unsigned operator()(f_app const& a) const;
unsigned operator()(expr* const* args) const { return 14; }
unsigned operator()(expr* const* args, unsigned idx) const { return args[idx]->hash(); }
};
class theory_plugin {
protected:
typedef hashtable<f_app, f_app_hash, f_app_eq> table;
ast_manager& m;
smtfd_abs& m_abs;
expr_ref_vector& m_lemmas;
model_ref m_model;
expr_ref_vector m_values;
ast_ref_vector m_pinned;
expr_ref_vector m_args, m_args2, m_vargs;
f_app_eq m_eq;
f_app_hash m_hash;
scoped_ptr_vector<table> m_tables;
obj_map<ast, unsigned> m_ast2table;
table& ast2table(ast* f) {
unsigned idx = 0;
if (!m_ast2table.find(f, idx)) {
idx = m_tables.size();
m_tables.push_back(alloc(table, DEFAULT_HASHTABLE_INITIAL_CAPACITY, m_hash, m_eq));
m_ast2table.insert(f, idx);
m_pinned.push_back(f);
}
return *m_tables[idx];
}
f_app mk_app(ast* f, app* t) {
f_app r;
r.m_f = f;
r.m_val_offset = m_values.size();
r.m_t = t;
for (expr* arg : *t) {
m_values.push_back(eval_abs(arg));
}
m_values.push_back(eval_abs(t));
return r;
}
f_app const& insert(f_app const& f) {
return ast2table(f.m_f).insert_if_not_there(f);
}
public:
theory_plugin(smtfd_abs& a, expr_ref_vector& lemmas, model* mdl) :
m(lemmas.get_manager()),
m_abs(a),
m_lemmas(lemmas),
m_model(mdl),
m_values(m),
m_pinned(m),
m_args(m), m_args2(m), m_vargs(m),
m_eq(*this),
m_hash(*this)
{}
expr_ref_vector const& values() const { return m_values; }
ast_manager& get_manager() { return m; }
void add_lemma(expr* fml) {
expr_ref _fml(fml, m);
TRACE("smtfd", tout << _fml << "\n";);
m_lemmas.push_back(m_abs.abs(fml));
}
expr_ref eval_abs(expr* t) { return (*m_model)(m_abs.abs(t)); }
expr* value_of(f_app const& f) const { return m_values[f.m_val_offset + f.m_t->get_num_args()]; }
void check_ackerman(ast* f, app* t) {
f_app f1 = mk_app(f, t);
f_app const& f2 = insert(f1);
if (f2.m_val_offset == f1.m_val_offset) {
return;
}
bool eq = value_of(f1) == value_of(f2);
m_values.shrink(f1.m_val_offset);
if (eq) {
return;
}
m_args.reset();
for (unsigned i = 0; i < t->get_num_args(); ++i) {
m_args.push_back(m.mk_eq(f1.m_t->get_arg(i), f2.m_t->get_arg(i)));
}
add_lemma(m.mk_implies(mk_and(m_args), m.mk_eq(f1.m_t, f2.m_t)));
}
virtual void check_term(expr* t, unsigned round) = 0;
virtual unsigned max_rounds() = 0;
};
bool f_app_eq::operator()(f_app const& a, f_app const& b) const {
if (a.m_f != b.m_f)
return false;
for (unsigned i = 0; i < a.m_t->get_num_args(); ++i) {
if (p.values().get(a.m_val_offset+i) != p.values().get(b.m_val_offset+i))
return false;
if (p.get_manager().get_sort(a.m_t->get_arg(i)) != p.get_manager().get_sort(b.m_t->get_arg(i)))
return false;
}
return true;
}
unsigned f_app_hash::operator()(f_app const& a) const {
return get_composite_hash(p.values().c_ptr() + a.m_val_offset, a.m_t->get_num_args(), *this, *this);
}
class uf_plugin : public theory_plugin {
bool is_uf(expr* t) {
return is_app(t) && to_app(t)->get_family_id() == null_family_id && to_app(t)->get_num_args() > 0;
}
public:
uf_plugin(smtfd_abs& a, expr_ref_vector& lemmas, model* mdl):
theory_plugin(a, lemmas, mdl)
{}
void check_term(expr* t, unsigned round) override {
if (round == 0 && is_uf(t))
check_ackerman(to_app(t)->get_decl(), to_app(t));
}
unsigned max_rounds() override { return 1; }
};
class a_plugin : public theory_plugin {
array_util m_autil;
th_rewriter m_rewriter;
void check_select(app* t) {
expr* a = t->get_arg(0);
expr_ref vA = eval_abs(a);
check_ackerman(vA, t);
}
// check that (select(t, t.args) = t.value)
void check_store0(app * t) {
SASSERT(m_autil.is_store(t));
m_args.reset();
m_args.push_back(t);
for (unsigned i = 1; i + 1 < t->get_num_args(); ++i) {
m_args.push_back(t->get_arg(i));
}
app_ref sel(m_autil.mk_select(m_args), m);
expr* stored_value = t->get_arg(t->get_num_args()-1);
expr_ref val1 = eval_abs(sel);
expr_ref val2 = eval_abs(stored_value);
if (val1 != val2) {
add_lemma(m.mk_eq(sel, stored_value));
}
}
/**
every t and a must agree with select values that
are different from updates in t.
let t := store(B, i, v)
add axioms of the form:
i = j or A != B or store(B,i,v)[j] = A[j]
where j is in tableA and value equal to some index in tableT
*/
void check_store1(app* t) {
SASSERT(m_autil.is_store(t));
expr* arg = t->get_arg(0);
expr_ref vT = eval_abs(t);
expr_ref vA = eval_abs(arg);
if (vT == vA) {
return;
}
table& tT = ast2table(vT); // select table of t
table& tA = ast2table(vA); // select table of arg
m_vargs.reset();
m_args.reset();
m_args.push_back(t);
for (unsigned i = 0; i + 1 < t->get_num_args(); ++i) {
m_vargs.push_back(eval_abs(t->get_arg(i)));
m_args.push_back(t->get_arg(i));
}
for (auto& fA : tA) {
f_app fT;
if (tT.find(fA, fT) && value_of(fA) != value_of(fT) && !eq(m_vargs, fA)) {
SASSERT(same_array_sort(fA, fT));
m_args2.reset();
for (unsigned i = 0; i < t->get_num_args(); ++i) {
m_args2.push_back(fA.m_t->get_arg(i));
}
expr_ref eq = mk_eq_idxs(m_args, m_args2);
m_args2[0] = t;
add_lemma(m.mk_implies(m.mk_eq(t->get_arg(0), fA.m_t->get_arg(0)), m.mk_or(eq, m.mk_eq(fA.m_t, m_autil.mk_select(m_args2)))));
}
}
}
bool same_array_sort(f_app const& fA, f_app const& fT) const {
return m.get_sort(fA.m_t->get_arg(0)) == m.get_sort(fT.m_t->get_arg(0));
}
/**
Enforce M[x] == rewrite(M[x]) for every A[x] such that M = A under current model.
*/
void beta_reduce(expr* t) {
bool added = false;
if (m_autil.is_map(t) ||
is_lambda(t)) {
expr_ref vT = eval_abs(t);
table& tT = ast2table(vT);
for (f_app & f : tT) {
if (m.get_sort(t) != m.get_sort(f.m_t->get_arg(0)))
continue;
m_args.reset();
m_args.append(f.m_t->get_num_args(), f.m_t->get_args());
m_args[0] = t;
expr_ref sel(m_autil.mk_select(m_args), m);
expr_ref selr = sel;
m_rewriter(selr);
expr_ref vS = eval_abs(sel);
expr_ref vR = eval_abs(selr);
if (vS != vR) {
add_lemma(m.mk_eq(sel, selr));
}
}
}
}
bool eq(expr_ref_vector const& args, f_app const& f) {
SASSERT(args.size() == f.m_t->get_num_args());
for (unsigned i = 0, sz = args.size(); i < sz; ++i) {
if (args.get(i) != m_values.get(f.m_val_offset + 1))
return false;
}
return true;
}
expr_ref mk_eq_idxs(expr_ref_vector const& es1, expr_ref_vector const& es2) {
SASSERT(es1.size() == es2.size());
expr_ref_vector r(m);
for (unsigned i = es1.size(); i-- > 1; ) {
r.push_back(m.mk_eq(es1[i], es2[i]));
}
return mk_and(r);
}
public:
a_plugin(smtfd_abs& a, expr_ref_vector& lemmas, model* mdl):
theory_plugin(a, lemmas, mdl),
m_autil(m),
m_rewriter(m)
{}
void check_term(expr* t, unsigned round) override {
switch (round) {
case 0:
if (m_autil.is_select(t)) {
check_select(to_app(t));
}
if (m_autil.is_store(t)) {
check_store0(to_app(t));
}
break;
case 1:
if (m_autil.is_store(t)) {
check_store1(to_app(t));
}
else {
beta_reduce(t);
}
break;
default:
break;
}
}
// TBD: enforce extensionality
unsigned max_rounds() override { return 2; }
};
struct stats {
unsigned m_num_lemmas;
unsigned m_num_rounds;
stats() { memset(this, 0, sizeof(stats)); }
};
class solver : public solver_na2as {
ast_manager& m;
smtfd_abs m_abs;
ref<::solver> m_fd_solver;
ref<::solver> m_smt_solver;
expr_ref_vector m_assertions;
unsigned_vector m_assertions_lim;
unsigned m_assertions_qhead;
expr_ref_vector m_toggles;
expr_ref m_toggle, m_not_toggle;
model_ref m_model;
std::string m_reason_unknown;
unsigned m_max_lemmas;
stats m_stats;
unsigned m_useful_smt, m_non_useful_smt, m_max_conflicts;
bool m_smt_known;
void flush_assertions() {
SASSERT(m_assertions_qhead <= m_assertions.size());
unsigned sz = m_assertions.size() - m_assertions_qhead;
if (sz > 0) {
m_assertions.push_back(m_toggle);
expr_ref fml(m.mk_and(sz + 1, m_assertions.c_ptr() + m_assertions_qhead), m);
m_assertions.pop_back();
m_toggle = m.mk_fresh_const("toggle", m.mk_bool_sort());
m_not_toggle = m.mk_not(m_toggle);
m_not_toggle = abs(m_not_toggle);
m_assertions_qhead = m_assertions.size();
fml = m.mk_iff(m_toggle, fml);
assert_fd(abs(fml));
}
}
lbool check_abs(unsigned num_assumptions, expr * const * assumptions) {
expr_ref_vector asms(m);
init_assumptions(num_assumptions, assumptions, asms);
TRACE("smtfd", display(tout << asms););
SASSERT(asms.contains(m_toggle));
lbool r = m_fd_solver->check_sat(asms);
update_reason_unknown(r, m_fd_solver);
return r;
}
// not necessarily prime
lbool get_prime_implicate(unsigned num_assumptions, expr * const * assumptions, expr_ref_vector& core) {
expr_ref_vector asms(m);
m_fd_solver->get_model(m_model);
init_literals(num_assumptions, assumptions, asms);
TRACE("smtfd", display(tout << asms););
SASSERT(asms.contains(m_not_toggle));
lbool r = m_fd_solver->check_sat(asms);
update_reason_unknown(r, m_fd_solver);
if (r == l_false) {
m_fd_solver->get_unsat_core(core);
TRACE("smtfd", display(tout << core););
core.erase(m_not_toggle);
SASSERT(!asms.contains(m_not_toggle));
SASSERT(!asms.contains(m_toggle));
}
return r;
}
lbool check_smt(expr_ref_vector& core) {
rep(core);
TRACE("smtfd", tout << "core: " << core << "\n";);
IF_VERBOSE(10, verbose_stream() << "core: " << core << "\n");
params_ref p;
p.set_uint("max_conflicts", m_max_conflicts);
m_smt_solver->updt_params(p);
lbool r = m_smt_solver->check_sat(core);
update_reason_unknown(r, m_smt_solver);
m_smt_known = true;
if (r == l_false) {
unsigned sz0 = core.size();
m_smt_solver->get_unsat_core(core);
TRACE("smtfd", display(tout << core););
unsigned sz1 = core.size();
if (sz1 < sz0) {
++m_useful_smt;
m_max_conflicts += 10;
}
else {
++m_non_useful_smt;
if (m_max_conflicts > 200) m_max_conflicts -= 5;
}
}
if (r == l_undef) {
++m_non_useful_smt;
m_max_conflicts -= 5;
if (m_max_conflicts > 200) m_max_conflicts -= 5;
r = l_false;
m_smt_known = false;
}
return r;
}
bool add_theory_lemmas(expr_ref_vector const& core) {
expr_ref_vector lemmas(m);
a_plugin ap(m_abs, lemmas, m_model.get());
uf_plugin uf(m_abs, lemmas, m_model.get());
unsigned max_rounds = std::max(ap.max_rounds(), uf.max_rounds());
for (unsigned round = 0; round < max_rounds; ++round) {
for (expr* t : subterms(core)) {
if (lemmas.size() >= m_max_lemmas)
break;
ap.check_term(t, round);
uf.check_term(t, round);
}
}
for (expr* f : lemmas) {
IF_VERBOSE(10, verbose_stream() << "lemma: " << expr_ref(rep(f), m) << "\n");
assert_fd(f);
}
m_stats.m_num_lemmas += lemmas.size();
return !lemmas.empty();
}
void init_assumptions(unsigned sz, expr* const* user_asms, expr_ref_vector& asms) {
asms.reset();
asms.push_back(m_toggle);
for (unsigned i = 0; i < sz; ++i) {
asms.push_back(abs(user_asms[i]));
}
}
void init_literals(unsigned sz, expr* const* user_asms, expr_ref_vector& asms) {
asms.reset();
asms.push_back(m_not_toggle);
for (unsigned i = 0; i < sz; ++i) {
asms.push_back(abs(user_asms[i]));
}
for (expr* a : m_abs.atoms()) {
if (m_model->is_true(a)) {
asms.push_back(a);
}
else {
asms.push_back(m.mk_not(a));
}
}
asms.erase(m_toggle);
}
void checkpoint() {
if (m.canceled()) {
throw tactic_exception(m.limit().get_cancel_msg());
}
}
expr* rep(expr* e) { return m_abs.rep(e); }
expr* abs(expr* e) { return m_abs.abs(e); }
expr_ref_vector& rep(expr_ref_vector& v) { for (unsigned i = v.size(); i-- > 0; ) v[i] = rep(v.get(i)); return v; }
expr_ref_vector& abs(expr_ref_vector& v) { for (unsigned i = v.size(); i-- > 0; ) v[i] = abs(v.get(i)); return v; }
void init() {
if (!m_fd_solver) {
m_fd_solver = mk_fd_solver(m, get_params());
m_smt_solver = mk_smt_solver(m, get_params(), symbol::null);
m_smt_solver->updt_params(get_params());
}
}
std::ostream& display(std::ostream& out) {
init();
m_fd_solver->display(out);
m_smt_solver->display(out);
out << m_assumptions << "\n";
m_abs.display(out);
return out;
}
void update_reason_unknown(lbool r, ::solver_ref& s) {
if (r == l_undef) m_reason_unknown = s->reason_unknown();
}
public:
solver(ast_manager& m, params_ref const& p):
solver_na2as(m),
m(m),
m_assertions(m),
m_assertions_qhead(0),
m_abs(m),
m_toggles(m),
m_toggle(m.mk_true(), m),
m_not_toggle(m.mk_false(), m),
m_useful_smt(0),
m_non_useful_smt(0),
m_max_conflicts(500)
{
m_max_lemmas = 10;
updt_params(p);
}
~solver() override {}
::solver* translate(ast_manager& dst_m, params_ref const& p) override {
solver* result = alloc(solver, dst_m, p);
if (m_smt_solver) result->m_smt_solver = m_smt_solver->translate(dst_m, p);
if (m_fd_solver) result->m_fd_solver = m_fd_solver->translate(dst_m, p);
return result;
}
void assert_expr_core(expr* t) override {
m_assertions.push_back(t);
}
void push_core() override {
init();
flush_assertions();
m_toggles.push_back(m_toggle);
m_abs.push();
m_fd_solver->push();
m_smt_solver->push();
m_assertions_lim.push_back(m_assertions.size());
}
void pop_core(unsigned n) override {
m_fd_solver->pop(n);
m_smt_solver->pop(n);
m_abs.pop(n);
m_toggle = m_toggles.get(m_toggles.size() - n);
m_not_toggle = m.mk_not(m_toggle);
m_toggles.shrink(m_toggles.size() - n);
m_assertions.shrink(m_assertions_lim[m_assertions_lim.size() - n]);
m_assertions_lim.shrink(m_assertions_lim.size() - n);
m_assertions_qhead = m_assertions.size();
}
void assert_fd(expr* fml) {
m_fd_solver->assert_expr(fml);
for (expr* f : m_abs.atom_defs()) {
m_fd_solver->assert_expr(f);
}
m_abs.reset_atom_defs();
}
lbool check_sat_core2(unsigned num_assumptions, expr * const * assumptions) override {
init();
flush_assertions();
lbool r;
expr_ref_vector core(m);
while (true) {
IF_VERBOSE(1, verbose_stream() << "(smtfd-check-sat " << m_stats.m_num_rounds << ")\n");
m_stats.m_num_rounds++;
checkpoint();
// phase 1: check sat of abs
r = check_abs(num_assumptions, assumptions);
if (r != l_true) {
return r;
}
// phase 2: find prime implicate over FD (abstraction)
r = get_prime_implicate(num_assumptions, assumptions, core);
if (r != l_false) {
return r;
}
// phase 3: prime implicate over SMT
r = check_smt(core);
if (r != l_false) {
return r;
}
// phase 4: add theory lemmas
if (add_theory_lemmas(core) || m_smt_known) {
assert_fd(m.mk_not(mk_and(abs(core))));
}
else {
m_max_conflicts *= 2;
}
}
return l_undef;
}
void updt_params(params_ref const & p) override {
::solver::updt_params(p);
if (m_fd_solver) {
m_fd_solver->updt_params(p);
m_smt_solver->updt_params(p);
}
m_max_lemmas = p.get_uint("max-lemmas", 10);
}
void collect_param_descrs(param_descrs & r) override {
init();
m_smt_solver->collect_param_descrs(r);
m_fd_solver->collect_param_descrs(r);
r.insert("max-lemmas", CPK_UINT, "maximal number of lemmas per round", "10");
}
void set_produce_models(bool f) override { }
void set_progress_callback(progress_callback * callback) override { }
void collect_statistics(statistics & st) const override {
m_fd_solver->collect_statistics(st);
m_smt_solver->collect_statistics(st);
st.update("smtfd-num-lemmas", m_stats.m_num_lemmas);
st.update("smtfd-num-rounds", m_stats.m_num_rounds);
}
void get_unsat_core(expr_ref_vector & r) override {
m_fd_solver->get_unsat_core(r);
r.erase(m_toggle);
rep(r);
}
void get_model_core(model_ref & mdl) override {
SASSERT(m_smt_solver);
m_smt_solver->get_model(mdl);
}
model_converter_ref get_model_converter() const override {
SASSERT(m_smt_solver);
return m_smt_solver->get_model_converter();
}
proof * get_proof() override { return nullptr; }
std::string reason_unknown() const override { return m_reason_unknown; }
void set_reason_unknown(char const* msg) override { m_reason_unknown = msg; }
void get_labels(svector<symbol> & r) override { init(); m_smt_solver->get_labels(r); }
ast_manager& get_manager() const override { return m; }
lbool find_mutexes(expr_ref_vector const& vars, vector<expr_ref_vector>& mutexes) override {
return l_undef;
}
expr_ref_vector cube(expr_ref_vector& vars, unsigned backtrack_level) override {
return expr_ref_vector(m);
}
lbool get_consequences_core(expr_ref_vector const& asms, expr_ref_vector const& vars, expr_ref_vector& consequences) override {
return l_undef;
}
void get_levels(ptr_vector<expr> const& vars, unsigned_vector& depth) override {
init();
m_smt_solver->get_levels(vars, depth);
}
expr_ref_vector get_trail() override {
init();
return m_smt_solver->get_trail();
}
unsigned get_num_assertions() const override {
return m_assertions.size();
}
expr * get_assertion(unsigned idx) const override {
return m_assertions.get(idx);
}
};
}
solver * mk_smtfd_solver(ast_manager & m, params_ref const & p) {
return alloc(smtfd::solver, m, p);
}
tactic * mk_smtfd_tactic(ast_manager & m, params_ref const & p) {
return mk_solver2tactic(mk_smtfd_solver(m, p));
}

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src/tactic/fd_solver/smtfd_solver.h Normal file
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/*++
Copyright (c) 2019 Microsoft Corporation
Module Name:
smtfd_solver.h
Abstract:
SMT reduction to Finite domain solver.
Author:
Nikolaj Bjorner (nbjorner) 2019-09-03
Notes:
--*/
#ifndef SMTFD_SOLVER_H_
#define SMTFD_SOLVER_H_
#include "ast/ast.h"
#include "util/params.h"
class solver;
class tactic;
solver * mk_smtfd_solver(ast_manager & m, params_ref const & p);
tactic * mk_smtfd_tactic(ast_manager & m, params_ref const & p);
/*
ADD_TACTIC("smtfd", "builtin strategy for solving SMT problems by reduction to FD.", "mk_smtfd_tactic(m, p)")
*/
#endif