updates to sls

Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>

src/ast/simplifiers/solve_eqs.cpp

@@ -329,6 +329,7 @@ namespace euf {
         m_config.m_context_solve = p.get_bool("context_solve", tp.solve_eqs_context_solve());
         for (auto* ex : m_extract_plugins)
             ex->updt_params(p);
+        m_rewriter.updt_params(p);
     }
 
     void solve_eqs::collect_param_descrs(param_descrs& r) {

src/ast/sls/bv_sls.cpp

@@ -25,12 +25,15 @@ Author:
 
 namespace bv {
 
-    sls::sls(ast_manager& m): 
+    sls::sls(ast_manager& m, params_ref const& p): 
         m(m), 
         bv(m),
         m_terms(m),
-        m_eval(m)
+        m_eval(m),
-    {}
+        m_engine(m, p)
+    {
+        updt_params(p);
+    }
 
     void sls::init() {
         m_terms.init(); 
@@ -67,20 +70,48 @@ namespace bv {
         }
     }
 
+    void sls::init_repair_candidates() {
+        m_to_repair.reset();
+        ptr_vector<expr> todo;
+        expr_fast_mark1 mark;
+        for (auto index : m_repair_roots) 
+            todo.push_back(m_terms.term(index));
+        for (unsigned i = 0; i < todo.size(); ++i) {
+            expr* e = todo[i];
+            if (mark.is_marked(e))
+                continue;
+            mark.mark(e);
+            if (!is_app(e))
+                continue;
+            for (expr* arg : *to_app(e))
+                todo.push_back(arg);
+
+            if (is_uninterp_const(e))
+                m_to_repair.insert(e->get_id());
+
+        }
+    }
+
+
     void sls::reinit_eval() {
+        init_repair_candidates();
+
+        if (m_to_repair.empty())
+            return;
+           
         std::function<bool(expr*, unsigned)> eval = [&](expr* e, unsigned i) {
-            auto should_keep = [&]() {
+            unsigned id = e->get_id();
-                return m_rand() % 100 <= 92;
+            bool keep = (m_rand() % 100 <= 50) || !m_to_repair.contains(id);
-            };
+            if (m.is_bool(e) && (m_eval.is_fixed0(e) || keep))
-            if (m.is_bool(e)) {
+                return m_eval.bval0(e);
-                if (m_eval.is_fixed0(e) || should_keep())
-                    return m_eval.bval0(e);
-            }
             else if (bv.is_bv(e)) {
                 auto& w = m_eval.wval(e);
-                if (w.fixed.get(i) || should_keep())
+                if (w.fixed.get(i) || keep)
-                    return w.get_bit(i);                
+                    return w.get_bit(i);
-            }
+                //auto const& z = m_engine.get_value(e);
+                //return rational(z).get_bit(i);
+            }            
+            
             return m_rand() % 2 == 0;
         };
         m_eval.init_eval(m_terms.assertions(), eval);
@@ -119,7 +150,7 @@ namespace bv {
         return { false, nullptr };
     }
 
-    lbool sls::search() {
+    lbool sls::search1() {
         // init and init_eval were invoked
         unsigned n = 0;
         for (; n++ < m_config.m_max_repairs && m.inc(); ) {
@@ -127,7 +158,6 @@ namespace bv {
             if (!e)
                 return l_true;
 
-
             trace_repair(down, e);
 
             ++m_stats.m_moves;
@@ -140,16 +170,32 @@ namespace bv {
         return l_undef;
     }
 
+    lbool sls::search2() {
+        lbool res = l_undef;
+        if (m_stats.m_restarts == 0)
+            res = m_engine();
+        else if (m_stats.m_restarts % 1000 == 0)
+            res = m_engine.search_loop();
+        if (res != l_undef) 
+            m_engine_model = true;          
+        return res;
+    }
+
 
     lbool sls::operator()() {
         lbool res = l_undef;
         m_stats.reset();
         m_stats.m_restarts = 0;
+        m_engine_model = false;
+
         do {
-            res = search();
+            res = search1();
             if (res != l_undef)
                 break;
             trace();
+            res = search2();
+            if (res != l_undef)
+                break;
             reinit_eval();
         } 
         while (m.inc() && m_stats.m_restarts++ < m_config.m_max_restarts);
@@ -158,34 +204,60 @@ namespace bv {
     }
 
     void sls::try_repair_down(app* e) {
-
         unsigned n = e->get_num_args();
         if (n == 0) {
-            if (m.is_bool(e)) 
+            if (m.is_bool(e)) {
-                m_eval.set(e, m_eval.bval1(e));                            
+                m_eval.set(e, m_eval.bval1(e));
-            else 
+            }
+            else {
                 VERIFY(m_eval.wval(e).commit_eval());
+            }
             
             for (auto p : m_terms.parents(e))
                 m_repair_up.insert(p->get_id());
+            
             return;
         }        
 
-        unsigned s = m_rand(n);
+        if (n == 2) {
-        for (unsigned i = 0; i < n; ++i) {
+            auto d1 = get_depth(e->get_arg(0));
-            auto j = (i + s) % n;
+            auto d2 = get_depth(e->get_arg(1));
-            if (m_eval.try_repair(e, j)) {
+            unsigned s = m_rand(d1 + d2 + 2);
-                set_repair_down(e->get_arg(j));
+            if (s <= d1 && m_eval.try_repair(e, 0)) {
+                set_repair_down(e->get_arg(0));
+                return;
+            }
+            if (m_eval.try_repair(e, 1)) {
+                set_repair_down(e->get_arg(1));
+                return;
+            }
+            if (m_eval.try_repair(e, 0)) {
+                set_repair_down(e->get_arg(0));
                 return;
             }
         }
-        // search a new root / random walk to repair        
+        else {
+            unsigned s = m_rand(n);
+            for (unsigned i = 0; i < n; ++i) {
+                auto j = (i + s) % n;
+                if (m_eval.try_repair(e, j)) {
+                    set_repair_down(e->get_arg(j));
+                    return;
+                }
+            }
+        }
+        // repair was not successful, so reset the state to find a different way to repair
+        init_repair();
     }
 
     void sls::try_repair_up(app* e) {       
         
-        if (m_terms.is_assertion(e) || !m_eval.repair_up(e)) 
+        if (m_terms.is_assertion(e)) 
-            m_repair_roots.insert(e->get_id());        
+            m_repair_roots.insert(e->get_id());    
+        else if (!m_eval.repair_up(e)) {
+            //m_repair_roots.insert(e->get_id());
+            init_repair();
+        }
         else {
             if (!eval_is_correct(e)) {
                 verbose_stream() << "incorrect eval #" << e->get_id() << " " << mk_bounded_pp(e, m) << "\n";
@@ -224,7 +296,10 @@ namespace bv {
     }
 
     model_ref sls::get_model() {
-        model_ref mdl = alloc(model, m);
+        if (m_engine_model)
+            return m_engine.get_model();
+
+        model_ref mdl = alloc(model, m);         
         auto& terms = m_eval.sort_assertions(m_terms.assertions());
         for (expr* e : terms) {
             if (!re_eval_is_correct(to_app(e))) {
@@ -273,7 +348,12 @@ namespace bv {
     void sls::updt_params(params_ref const& _p) {
         sls_params p(_p);
         m_config.m_max_restarts = p.max_restarts();
+        m_config.m_max_repairs = p.max_repairs();
         m_rand.set_seed(p.random_seed());
+        m_terms.updt_params(_p);
+        params_ref q = _p;
+        q.set_uint("max_restarts", 10);
+        m_engine.updt_params(q);
     }
 
     void sls::trace_repair(bool down, expr* e) {

src/ast/sls/bv_sls.h

@@ -26,6 +26,7 @@ Author:
 #include "ast/sls/sls_valuation.h"
 #include "ast/sls/bv_sls_terms.h"
 #include "ast/sls/bv_sls_eval.h"
+#include "ast/sls/sls_engine.h"
 #include "ast/bv_decl_plugin.h"
 #include "model/model.h"
 
@@ -49,6 +50,8 @@ namespace bv {
         ptr_vector<expr>    m_todo;
         random_gen          m_rand;
         config              m_config;
+        sls_engine          m_engine;
+        bool                m_engine_model = false;
         
         std::pair<bool, app*> next_to_repair();
         
@@ -59,19 +62,23 @@ namespace bv {
         void try_repair_up(app* e);
         void set_repair_down(expr* e) { m_repair_down = e->get_id(); }
 
-        lbool search();
+        lbool search1();
+        lbool search2();
         void reinit_eval();
         void init_repair();
         void trace();
         void trace_repair(bool down, expr* e);
 
+        indexed_uint_set m_to_repair;
+        void init_repair_candidates();
+
     public:
-        sls(ast_manager& m);
+        sls(ast_manager& m, params_ref const& p);
                 
         /**
         * Add constraints
         */
-        void assert_expr(expr* e) { m_terms.assert_expr(e); }
+        void assert_expr(expr* e) { m_terms.assert_expr(e); m_engine.assert_expr(e); }
 
         /*
         * Invoke init after all expressions are asserted. 
@@ -91,10 +98,10 @@ namespace bv {
         lbool operator()();
 
         void updt_params(params_ref const& p);
-        void collect_statistics(statistics & st) const { m_stats.collect_statistics(st); }
+        void collect_statistics(statistics& st) const { m_stats.collect_statistics(st); m_engine.collect_statistics(st); }
-        void reset_statistics() { m_stats.reset(); }
+        void reset_statistics() { m_stats.reset(); m_engine.reset_statistics(); }
 
-        sls_stats const& get_stats() const { return m_stats; }
+        unsigned get_num_moves() { return m_stats.m_moves + m_engine.get_stats().m_moves; }
 
         std::ostream& display(std::ostream& out);
 

src/ast/sls/bv_sls_eval.cpp

@@ -24,8 +24,8 @@ namespace bv {
     {}   
 
     void sls_eval::init_eval(expr_ref_vector const& es, std::function<bool(expr*, unsigned)> const& eval) {
-        sort_assertions(es);
+        auto& terms = sort_assertions(es);
-        for (expr* e : m_todo) {
+        for (expr* e : terms) {
             if (!is_app(e))
                 continue;
             app* a = to_app(e);
@@ -49,7 +49,7 @@ namespace bv {
                 TRACE("sls", tout << "Unhandled expression " << mk_pp(e, m) << "\n");
             }
         }
-        m_todo.reset();
+        terms.reset();
     }
 
     /**
@@ -1698,7 +1698,7 @@ namespace bv {
         }
         if (bv.is_bv(e)) {
             auto& v = eval(to_app(e));
-            // verbose_stream() << "committing: " << v << "\n";
+            
             for (unsigned i = 0; i < v.nw; ++i)
                 if (0 != (v.fixed[i] & (v.bits()[i] ^ v.eval[i]))) {
                     v.bits().copy_to(v.nw, v.eval);

src/ast/sls/bv_sls_fixed.cpp

@@ -108,6 +108,13 @@ namespace bv {
             else if (bv.is_numeral(t, a))
                 init_range(s, -a, nullptr, rational(0), false);
         }
+        else if (sign && m.is_eq(e, s, t)) {
+            if (bv.is_numeral(s, a))
+                // 1 <= t - a
+                init_range(nullptr, rational(1), t, -a, false);
+            else if (bv.is_numeral(t, a))
+                init_range(nullptr, rational(1), s, -a, false);
+        }
         else if (bv.is_bit2bool(e, s, idx)) {
             auto& val = wval(s);
             val.try_set_bit(idx, !sign);
@@ -157,7 +164,6 @@ namespace bv {
             else
                 v.add_range(-b, -a);
         }
-        
     }
 
     void sls_fixed::get_offset(expr* e, expr*& x, rational& offset) {

src/ast/sls/bv_sls_terms.cpp

@@ -20,12 +20,14 @@ Author:
 
 #include "ast/ast_ll_pp.h"
 #include "ast/sls/bv_sls.h"
+#include "ast/rewriter/th_rewriter.h"
 
 namespace bv {
 
     sls_terms::sls_terms(ast_manager& m): 
         m(m), 
         bv(m),
+        m_rewriter(m),
         m_assertions(m),
         m_pinned(m),
         m_translated(m), 
@@ -40,18 +42,20 @@ namespace bv {
         expr* top = e;
         m_pinned.push_back(e);
         m_todo.push_back(e);
-        expr_fast_mark1 mark;
+        {
-        for (unsigned i = 0; i < m_todo.size(); ++i) {
+            expr_fast_mark1 mark;
-            expr* e = m_todo[i];
+            for (unsigned i = 0; i < m_todo.size(); ++i) {
-            if (!is_app(e))
+                expr* e = m_todo[i];
-                continue;
+                if (!is_app(e))
-            if (m_translated.get(e->get_id(), nullptr))
+                    continue;
-                continue;
+                if (m_translated.get(e->get_id(), nullptr))
-            if (mark.is_marked(e))
+                    continue;
-                continue;
+                if (mark.is_marked(e))
-            mark.mark(e);
+                    continue;
-            for (auto arg : *to_app(e))
+                mark.mark(e);
-                m_todo.push_back(arg);
+                for (auto arg : *to_app(e))
+                    m_todo.push_back(arg);
+            }
         }
         std::stable_sort(m_todo.begin(), m_todo.end(), [&](expr* a, expr* b) { return get_depth(a) < get_depth(b); });
         for (expr* e : m_todo)
@@ -127,7 +131,7 @@ namespace bv {
         m_translated.setx(e->get_id(), r);
     }
 
-    expr* sls_terms::mk_sdiv(expr* x, expr* y) {
+    expr_ref sls_terms::mk_sdiv(expr* x, expr* y) {
         // d = udiv(abs(x), abs(y))
         // y = 0, x >= 0 -> -1
         // y = 0, x < 0 -> 1
@@ -141,17 +145,18 @@ namespace bv {
         expr_ref z(bv.mk_zero(sz), m);
         expr* signx = bv.mk_ule(bv.mk_numeral(N / 2, sz), x);
         expr* signy = bv.mk_ule(bv.mk_numeral(N / 2, sz), y);
-        expr* absx = m.mk_ite(signx, bv.mk_bv_sub(bv.mk_numeral(N - 1, sz), x), x);
+        expr* absx = m.mk_ite(signx, bv.mk_bv_neg(x), x);
-        expr* absy = m.mk_ite(signy, bv.mk_bv_sub(bv.mk_numeral(N - 1, sz), y), y);
+        expr* absy = m.mk_ite(signy, bv.mk_bv_neg(y), y);
         expr* d = bv.mk_bv_udiv(absx, absy);
-        expr* r = m.mk_ite(m.mk_eq(signx, signy), d, bv.mk_bv_neg(d));
+        expr_ref r(m.mk_ite(m.mk_eq(signx, signy), d, bv.mk_bv_neg(d)), m);
         r = m.mk_ite(m.mk_eq(z, y),
-                m.mk_ite(signx, bv.mk_one(sz), bv.mk_numeral(N - 1, sz)),
+                     m.mk_ite(signx, bv.mk_one(sz), bv.mk_numeral(N - 1, sz)),
-                m.mk_ite(m.mk_eq(x, z), z, r));
+                     m.mk_ite(m.mk_eq(x, z), z, r));
+        m_rewriter(r);
         return r;
     }
 
-    expr* sls_terms::mk_smod(expr* x, expr* y) {
+    expr_ref sls_terms::mk_smod(expr* x, expr* y) {
         // u := umod(abs(x), abs(y))
         // u = 0 ->  0
         // y = 0 ->  x
@@ -164,21 +169,24 @@ namespace bv {
         expr_ref abs_x(m.mk_ite(bv.mk_sle(z, x), x, bv.mk_bv_neg(x)), m);
         expr_ref abs_y(m.mk_ite(bv.mk_sle(z, y), y, bv.mk_bv_neg(y)), m);
         expr_ref u(bv.mk_bv_urem(abs_x, abs_y), m);
-        return
+        expr_ref r(m);
-            m.mk_ite(m.mk_eq(u, z), z,
+        r = m.mk_ite(m.mk_eq(u, z), z,
                 m.mk_ite(m.mk_eq(y, z), x,
                     m.mk_ite(m.mk_and(bv.mk_sle(z, x), bv.mk_sle(z, x)), u,
                         m.mk_ite(bv.mk_sle(z, x), bv.mk_bv_add(y, u),
                             m.mk_ite(bv.mk_sle(z, y), bv.mk_bv_sub(y, u), bv.mk_bv_neg(u))))));
-                      
+        m_rewriter(r);
+        return r;
     }
 
-    expr* sls_terms::mk_srem(expr* x, expr* y) {
+    expr_ref sls_terms::mk_srem(expr* x, expr* y) {
         // y = 0 -> x
         // else x - sdiv(x, y) * y
-        return 
+        expr_ref r(m);
-            m.mk_ite(m.mk_eq(y, bv.mk_zero(bv.get_bv_size(x))),
+        r = m.mk_ite(m.mk_eq(y, bv.mk_zero(bv.get_bv_size(x))),
                      x, bv.mk_bv_sub(x, bv.mk_bv_mul(y, mk_sdiv(x, y))));
+        m_rewriter(r);
+        return r;
     }
 
 
@@ -209,4 +217,11 @@ namespace bv {
             m_assertion_set.insert(a->get_id());
     }
 
+    void sls_terms::updt_params(params_ref const& p) {
+        params_ref q = p;
+        q.set_bool("flat", false);
+        m_rewriter.updt_params(q);
+    }
+
+
 }

src/ast/sls/bv_sls_terms.h

@@ -21,6 +21,7 @@ Author:
 #include "util/scoped_ptr_vector.h"
 #include "util/uint_set.h"
 #include "ast/ast.h"
+#include "ast/rewriter/th_rewriter.h"
 #include "ast/sls/sls_stats.h"
 #include "ast/sls/sls_powers.h"
 #include "ast/sls/sls_valuation.h"
@@ -31,6 +32,7 @@ namespace bv {
     class sls_terms {
         ast_manager&        m;
         bv_util             bv;
+        th_rewriter         m_rewriter;
         ptr_vector<expr>    m_todo, m_args;
         expr_ref_vector     m_assertions, m_pinned, m_translated;
         app_ref_vector      m_terms;
@@ -40,12 +42,14 @@ namespace bv {
         expr* ensure_binary(expr* e);
         void ensure_binary_core(expr* e);
 
-        expr* mk_sdiv(expr* x, expr* y);
+        expr_ref mk_sdiv(expr* x, expr* y);
-        expr* mk_smod(expr* x, expr* y);
+        expr_ref mk_smod(expr* x, expr* y);
-        expr* mk_srem(expr* x, expr* y);
+        expr_ref mk_srem(expr* x, expr* y);
 
     public:
         sls_terms(ast_manager& m);
+
+        void updt_params(params_ref const& p);
         
         /**
         * Add constraints

src/ast/sls/sls_engine.cpp

@@ -421,6 +421,7 @@ lbool sls_engine::search() {
 
         // get candidate variables
         ptr_vector<func_decl> & to_evaluate = m_tracker.get_unsat_constants(m_assertions);
+        
         if (to_evaluate.empty())
         {
             res = l_true;
@@ -514,6 +515,12 @@ lbool sls_engine::operator()() {
     if (m_restart_init)
         m_tracker.randomize(m_assertions);
 
+    return search_loop();
+}
+
+
+lbool sls_engine::search_loop() {
+
     lbool res = l_undef;
 
     do {
@@ -533,7 +540,6 @@ lbool sls_engine::operator()() {
     } while (res != l_true && m_stats.m_restarts++ < m_max_restarts);
 
     verbose_stream() << "(restarts: " << m_stats.m_restarts << " flips: " << m_stats.m_moves << " fps: " << (m_stats.m_moves / m_stats.m_stopwatch.get_current_seconds()) << ")" << std::endl;
-    
     return res;
 }
 

src/ast/sls/sls_engine.h

@@ -79,7 +79,11 @@ public:
     void mk_inv(unsigned bv_sz, const mpz & old_value, mpz & inverted);
     void mk_flip(sort * s, const mpz & old_value, unsigned bit, mpz & flipped);            
 
-    lbool search();
+
+
+    lbool search();  
+
+    lbool search_loop();
 
     lbool operator()();
 

src/ast/sls/sls_valuation.cpp

@@ -106,10 +106,12 @@ namespace bv {
 
     bool sls_valuation::commit_eval() { 
         for (unsigned i = 0; i < nw; ++i)
-            if (0 != (fixed[i] & (m_bits[i] ^ eval[i])))
+            if (0 != (fixed[i] & (m_bits[i] ^ eval[i])))                 
-                return false;        
+                return false;
-        if (!in_range(eval))
+            
+        if (!in_range(eval)) 
             return false;
+        
         for (unsigned i = 0; i < nw; ++i) 
             m_bits[i] = eval[i]; 
         SASSERT(well_formed()); 
@@ -491,8 +493,8 @@ namespace bv {
         SASSERT(well_formed());
     }
 
-    void sls_valuation::add_range(rational l, rational h) {
+    void sls_valuation::add_range(rational l, rational h) {              
-        
+
         l = mod(l, rational::power_of_two(bw));
         h = mod(h, rational::power_of_two(bw));
         if (h == l)
@@ -509,21 +511,28 @@ namespace bv {
             auto old_lo = lo();
             auto old_hi = hi();
             if (old_lo < old_hi) {
-                if (old_lo < l && l < old_hi)
+                if (old_lo < l && l < old_hi && old_hi <= h)
                     set_value(m_lo, l),
                     old_lo = l;
-                if (old_hi < h && h < old_hi)
+                if (l <= old_lo && old_lo < h && h < old_hi)
                     set_value(m_hi, h);
             }
             else {
                 SASSERT(old_hi < old_lo);
-                if (old_lo < l || l < old_hi)
+                if (h <= old_hi && old_lo <= l) {
-                    set_value(m_lo, l),
+                    set_value(m_lo, l);
-                    old_lo = l;
-                if (old_lo < h && h < old_hi)
                     set_value(m_hi, h);
-                else if (old_hi < old_lo && (h < old_hi || old_lo < h))
+                }
+                else if (old_lo <= l && l <= h) {
+                    set_value(m_lo, l);
                     set_value(m_hi, h);
+                }
+                else if (old_lo + 1 == l) {
+                    set_value(m_lo, l);
+                }
+                else if (old_hi == h + 1) {
+                    set_value(m_hi, h);
+                }
             }
         }
 
@@ -552,8 +561,7 @@ namespace bv {
     //  lo < hi, set most significant bits based on hi
     //
     void sls_valuation::tighten_range() {
-
+        
-        // verbose_stream() << "tighten " << *this << "\n";
         if (m_lo == m_hi)
             return;
 
@@ -613,6 +621,9 @@ namespace bv {
             break;
         }
 
+        if (has_range() && !in_range(m_bits)) 
+            m_bits = m_lo;
+        
         SASSERT(well_formed());
     }
 

src/params/sls_params.pyg

@@ -3,6 +3,7 @@ def_module_params('sls',
                   description='Experimental Stochastic Local Search Solver (for QFBV only).',
                   params=(max_memory_param(),
                         ('max_restarts', UINT, UINT_MAX, 'maximum number of restarts'),
+			('max_repairs', UINT, 1000, 'maximum number of repairs before restart'),
                         ('walksat', BOOL, 1, 'use walksat assertion selection (instead of gsat)'),
                         ('walksat_ucb', BOOL, 1, 'use bandit heuristic for walksat assertion selection (instead of random)'),
                         ('walksat_ucb_constant', DOUBLE, 20.0, 'the ucb constant c in the term score + c * f(touched)'),

src/sat/smt/sls_solver.cpp

@@ -61,9 +61,10 @@ namespace sls {
         m_m = alloc(ast_manager, m);
         ast_translation tr(m, *m_m);
         
+        params_ref p;
         m_completed = false;
         m_result = l_undef;
-        m_bvsls = alloc(bv::sls, *m_m);
+        m_bvsls = alloc(bv::sls, *m_m, p);
         // walk clauses, add them
         // walk trail stack until search level, add units
         // encapsulate bvsls within the arguments of run-local-search.

src/tactic/sls/sls_tactic.cpp

@@ -134,7 +134,7 @@ public:
     bv_sls_tactic(ast_manager& _m, params_ref const& p) :
         m(_m),
         m_params(p) {
-        m_sls = alloc(bv::sls, m);
+        m_sls = alloc(bv::sls, m, p);
     }
 
     tactic* translate(ast_manager& m) override {
@@ -172,12 +172,12 @@ public:
         m_sls->init_eval(false_eval);
 
         lbool res = m_sls->operator()();
-        auto const& stats = m_sls->get_stats();
-        report_tactic_progress("Number of flips:", stats.m_moves);
-        IF_VERBOSE(20, verbose_stream() << res << "\n");
-        IF_VERBOSE(20, m_sls->display(verbose_stream()));
         m_st.reset();
         m_sls->collect_statistics(m_st);
+        report_tactic_progress("Number of flips:", m_sls->get_num_moves());
+        IF_VERBOSE(20, verbose_stream() << res << "\n");
+        IF_VERBOSE(20, m_sls->display(verbose_stream()));
+
         if (res == l_true) {            
             if (g->models_enabled()) {
                 model_ref mdl = m_sls->get_model();
@@ -207,7 +207,7 @@ public:
 
     void cleanup() override {
 
-        auto* d = alloc(bv::sls, m);
+        auto* d = alloc(bv::sls, m, m_params);
         std::swap(d, m_sls);
         dealloc(d);
     }
@@ -235,12 +235,6 @@ tactic* mk_bv_sls_tactic(ast_manager& m, params_ref const& p) {
 
 
 static tactic * mk_preamble(ast_manager & m, params_ref const & p) {
-    params_ref main_p;
-    main_p.set_bool("elim_and", true);
-    // main_p.set_bool("pull_cheap_ite", true);
-    main_p.set_bool("push_ite_bv", true);
-    main_p.set_bool("blast_distinct", true);
-    main_p.set_bool("hi_div0", true);
 
     params_ref simp2_p = p;
     simp2_p.set_bool("som", true);
@@ -249,18 +243,15 @@ static tactic * mk_preamble(ast_manager & m, params_ref const & p) {
     simp2_p.set_bool("local_ctx", true);
     simp2_p.set_uint("local_ctx_limit", 10000000);
 
-    params_ref hoist_p;
+    params_ref hoist_p = p;
     hoist_p.set_bool("hoist_mul", true);
     hoist_p.set_bool("som", false);
 
-    params_ref gaussian_p;
+    params_ref gaussian_p = p;
     // conservative gaussian elimination. 
     gaussian_p.set_uint("gaussian_max_occs", 2); 
 
-    params_ref ctx_p;
+    return and_then(and_then(mk_simplify_tactic(m, p),                             
-    ctx_p.set_uint("max_depth", 32);
-    ctx_p.set_uint("max_steps", 5000000);
-    return and_then(and_then(mk_simplify_tactic(m),                             
                              mk_propagate_values_tactic(m),
                              using_params(mk_solve_eqs_tactic(m), gaussian_p),
                              mk_elim_uncnstr_tactic(m),
@@ -278,7 +269,9 @@ tactic * mk_qfbv_sls_tactic(ast_manager & m, params_ref const & p) {
 }
 
 tactic* mk_qfbv_new_sls_tactic(ast_manager& m, params_ref const& p) {
-    tactic* t = and_then(mk_preamble(m, p), mk_bv_sls_tactic(m, p));
+    params_ref q = p;
-    t->updt_params(p);
+    q.set_bool("elim_sign_ext", false);
+    tactic* t = and_then(mk_preamble(m, q), mk_bv_sls_tactic(m, q));
+    t->updt_params(q);
     return t;
 }