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Model reconstruction

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CEisenhofer 2026-03-11 18:13:16 +01:00
parent d23f376b39
commit 99727faf70
5 changed files with 164 additions and 14 deletions
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74
src/smt/nseq_model.cpp
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@ -35,6 +35,8 @@ namespace smt {
m_var_values.reset();
m_var_regex.reset();
m_trail.reset();
m_int_model = nullptr;
m_mg = &mg;
m_factory = alloc(seq_factory, m, m_th.get_family_id(), mg.get_model());
mg.register_factory(m_factory);
@ -42,12 +44,12 @@ namespace smt {
register_existing_values(nielsen);
collect_var_regex_constraints(state);
// solve integer constraints from the sat_path FIRST so that
// m_int_model is available when snode_to_value evaluates power exponents
nielsen.solve_sat_path_ints(m_int_model);
// extract variable assignments from the satisfying leaf's substitution path
seq::nielsen_node const* sat = nielsen.sat_node();
IF_VERBOSE(1, verbose_stream() << "nseq model init: sat_node=" << (sat ? "set" : "null")
<< " path_len=" << nielsen.sat_path().size() << "\n";);
extract_assignments(nielsen.sat_path());
IF_VERBOSE(1, verbose_stream() << "nseq model: m_var_values has " << m_var_values.size() << " entries\n";);
}
model_value_proc* nseq_model::mk_value(enode* n, model_generator& mg) {
@ -103,6 +105,8 @@ namespace smt {
m_var_values.reset();
m_var_regex.reset();
m_trail.reset();
m_int_model = nullptr;
m_mg = nullptr;
m_factory = nullptr;
}
@ -175,6 +179,68 @@ namespace smt {
return expr_ref(m);
}
if (n->is_power()) {
SASSERT(n->num_args() == 2);
// Evaluate the base and exponent to produce a concrete string.
// The base is a string snode; the exponent is an integer expression
// whose value comes from the sat_path integer model.
expr_ref base_val = snode_to_value(n->arg(0));
if (!base_val)
return expr_ref(m);
euf::snode* exp_snode = n->arg(1);
expr* exp_expr = exp_snode ? exp_snode->get_expr() : nullptr;
rational exp_val;
arith_util arith(m);
// Try to evaluate exponent: first check if it's a numeral,
// then try the int model from sat_path constraints,
// finally fall back to the proto_model from model_generator.
if (exp_expr && arith.is_numeral(exp_expr, exp_val)) {
// already concrete
} else if (exp_expr && m_int_model.get()) {
expr_ref result(m);
if (m_int_model->eval_expr(exp_expr, result, true) && arith.is_numeral(result, exp_val)) {
// evaluated from int model
} else if (m_mg) {
proto_model& pm = m_mg->get_model();
if (pm.eval(exp_expr, result, true) && arith.is_numeral(result, exp_val)) {
// evaluated from proto_model
} else {
exp_val = rational(0);
}
} else {
exp_val = rational(0);
}
} else if (exp_expr && m_mg) {
expr_ref result(m);
proto_model& pm = m_mg->get_model();
if (pm.eval(exp_expr, result, true) && arith.is_numeral(result, exp_val)) {
// evaluated from proto_model
} else {
exp_val = rational(0);
}
} else {
exp_val = rational(0);
}
if (exp_val.is_neg())
exp_val = rational(0);
// Build the repeated string: base^exp_val
if (exp_val.is_zero())
return expr_ref(m_seq.str.mk_empty(m_seq.str.mk_string_sort()), m);
if (exp_val.is_one())
return base_val;
// For small exponents, concatenate directly
unsigned n_val = exp_val.get_unsigned();
expr_ref acc(base_val);
for (unsigned i = 1; i < n_val; ++i)
acc = m_seq.str.mk_concat(acc, base_val);
return acc;
}
// fallback: use the underlying expression
expr* e = n->get_expr();
return e ? expr_ref(e, m) : expr_ref(m);