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Add a sharp throttle to lia2card tactic to control overhead in default tactic mode

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lia2card was added to qfuflia tactic based on a user scenario, but it overshot: lia2card is by default harmful. It is here tamed to only convert binary variables and throttle on nested ite terms
This commit is contained in:
Nikolaj Bjorner 2025-02-02 13:58:51 -08:00
parent fd2a8a554d
commit 99cbfa715c
3 changed files with 24 additions and 10 deletions
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2
src/params/tactic_params.pyg
View file

@ -9,6 +9,8 @@ def_module_params('tactic',
('blast_term_ite.max_inflation', UINT, UINT_MAX, "multiplicative factor of initial term size."),
('blast_term_ite.max_steps', UINT, UINT_MAX, "maximal number of steps allowed for tactic."),
('propagate_values.max_rounds', UINT, 4, "maximal number of rounds to propagate values."),
('lia2card.max_range', UINT, 100, "maximal range of integers to compilation into Booleans"),
('lia2card.max_ite_nesting', UINT, 4, "maximal nesting depth for ite expressions to be compiled into PB constraints"),
('default_tactic', SYMBOL, '', "overwrite default tactic in strategic solver"),
# ('aig.per_assertion', BOOL, True, "process one assertion at a time"),

23
src/tactic/arith/lia2card_tactic.cpp
View file

@ -25,6 +25,7 @@ Notes:
#include "ast/ast_util.h"
#include "ast/ast_pp_util.h"
#include "tactic/tactical.h"
#include "params/tactic_params.hpp"
#include "ast/simplifiers/bound_manager.h"
#include "ast/converters/generic_model_converter.h"
@ -116,7 +117,8 @@ public:
mutable ptr_vector<expr>* m_todo;
bounds_map m_bounds;
bool m_compile_equality;
unsigned m_max_ub;
unsigned m_max_range = 101;
unsigned m_max_ite_nesting = 1;
ref<generic_model_converter> m_mc;
lia2card_tactic(ast_manager & _m, params_ref const & p):
@ -126,7 +128,7 @@ public:
m_pb(m),
m_todo(alloc(ptr_vector<expr>)),
m_compile_equality(true) {
m_max_ub = 100;
updt_params(p);
}
~lia2card_tactic() override {
@ -137,7 +139,11 @@ public:
void updt_params(params_ref const & p) override {
m_params.append(p);
tactic_params tp(p);
m_compile_equality = m_params.get_bool("compile_equality", true);
m_max_range = tp.lia2card_max_range();
m_max_ite_nesting = tp.lia2card_max_ite_nesting();
}
expr_ref mk_bounded(expr_ref_vector& axioms, app* x, unsigned lo, unsigned hi) {
@ -152,7 +158,6 @@ public:
if (lo > 0) {
xs.push_back(a.mk_int(lo));
}
verbose_stream() << "bounded " << lo << " " << hi << "\n";
for (unsigned i = lo; i < hi; ++i) {
checkpoint();
@ -193,7 +198,7 @@ public:
if (a.is_int(x) &&
is_uninterp_const(x) &&
bounds.has_lower(x, lo, s1) && !s1 && lo.is_unsigned() &&
bounds.has_upper(x, hi, s2) && !s2 && hi.is_unsigned() && hi.get_unsigned() - lo.get_unsigned() <= m_max_ub) {
bounds.has_upper(x, hi, s2) && !s2 && hi.is_unsigned() && hi.get_unsigned() - lo.get_unsigned() <= m_max_range) {
expr_ref b = mk_bounded(axioms, to_app(x), lo.get_unsigned(), hi.get_unsigned());
rep.insert(x, b);
m_bounds.insert(x, bound(lo.get_unsigned(), hi.get_unsigned(), b));
@ -288,11 +293,14 @@ public:
rational r, q;
if (!is_app(x))
return false;
if (nesting > 8)
if (nesting > m_max_ite_nesting && !is_numeral(x, r))
return false;
app* f = to_app(x);
bool ok = true;
if (a.is_add(x)) {
if (is_numeral(x, r)) {
insert_arg(mul * r, conds, m.mk_true(), args, coeffs, coeff);
}
else if (a.is_add(x)) {
for (unsigned i = 0; ok && i < f->get_num_args(); ++i) {
ok = get_sum(nesting, f->get_arg(i), mul, conds, args, coeffs, coeff);
}
@ -321,9 +329,6 @@ public:
ok &= get_sum(nesting + 1, u, mul, conds, args, coeffs, coeff);
conds.pop_back();
}
else if (is_numeral(x, r)) {
insert_arg(mul*r, conds, m.mk_true(), args, coeffs, coeff);
}
else {
TRACE("pb", tout << "Can't handle " << mk_pp(x, m) << "\n";);
ok = false;

9
src/tactic/smtlogics/qflia_tactic.cpp
View file

@ -192,6 +192,11 @@ tactic * mk_preamble_tactic(ast_manager& m) {
ctx_simp_p.set_uint("max_depth", 30);
ctx_simp_p.set_uint("max_steps", 5000000);
// only binary integer variables are converted to PB
params_ref lia2card_p;
lia2card_p.set_uint("lia2card.max_range", 1);
lia2card_p.set_uint("lia2card.max_ite_nesting", 1);
return
and_then(
mk_simplify_tactic(m),
@ -199,7 +204,7 @@ tactic * mk_preamble_tactic(ast_manager& m) {
using_params(mk_ctx_simplify_tactic(m), ctx_simp_p),
using_params(mk_simplify_tactic(m), pull_ite_p),
mk_solve_eqs_tactic(m),
mk_lia2card_tactic(m),
mk_lia2card_tactic(m, lia2card_p),
mk_elim_uncnstr_tactic(m));
}
@ -209,6 +214,8 @@ tactic * mk_qflia_tactic(ast_manager & m, params_ref const & p) {
main_p.set_bool("som", true);
main_p.set_bool("blast_distinct", true);
main_p.set_uint("blast_distinct_threshold", 128);
main_p.set_uint("lia2card.max_range", 1);
main_p.set_uint("lia2card.max_ite_nesting", 1);
// main_p.set_bool("push_ite_arith", true);
params_ref quasi_pb_p;