separate fixed from bits to allow updates that break tabu

- range and fixed restrictions on terms are based on constraints and can be violated temporarily.
- bv_eval currently does not allow updating over fixed bits which leads to non-termination. TODO
- lookahead only considers tabu when setting values of variables.

src/ast/sls/sls_bv_plugin.cpp

@@ -62,6 +62,7 @@ namespace sls {
         auto a = to_app(e);
 
         if (!m_eval.eval_is_correct(a)) {
+            TRACE("sls", tout << "incorrect eval " << lit << ": " << mk_bounded_pp(e, m) << "\n";);
             IF_VERBOSE(20, verbose_stream() << "repair " << lit << " " << mk_bounded_pp(e, m) << "\n");
             ctx.new_value_eh(e);
         }
@@ -89,6 +90,7 @@ namespace sls {
         bool is_sat = true;
         for (auto t : ctx.subterms())
             if (is_app(t) && bv.is_bv(t) && to_app(t)->get_family_id() == bv.get_fid() && !m_eval.eval_is_correct(to_app(t))) {
+                TRACE("sls", tout << "incorrect eval: " << mk_bounded_pp(t, m) << " " << m_eval.wval(t) << "\n";);
                 ctx.new_value_eh(t);
                 is_sat = false;
             }
@@ -106,7 +108,7 @@ namespace sls {
         VERIFY(bv.is_numeral(v, val));
         auto& w = m_eval.eval(to_app(e));
         w.set_value(w.eval, val);
-        return w.commit_eval();
+        return w.commit_eval_check_tabu();
     }
 
     bool bv_plugin::repair_down(app* e) {