fix non-termination bug with retained clauses

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

src/ast/ast.cpp

@@ -2254,9 +2254,10 @@ func_decl * ast_manager::mk_fresh_func_decl(symbol const & prefix, symbol const
     }
     else {
         string_buffer<64> buffer;
-        buffer << prefix;
         if (prefix == symbol::null)
             buffer << "sk";
+        else
+            buffer << prefix;
         buffer << "!";
         if (suffix != symbol::null)
             buffer << suffix << "!";

src/ast/bv_decl_plugin.cpp

@@ -717,7 +717,7 @@ void bv_decl_plugin::get_op_names(svector<builtin_name> & op_names, symbol const
     op_names.push_back(builtin_name("rotate_left",OP_ROTATE_LEFT));
     op_names.push_back(builtin_name("rotate_right",OP_ROTATE_RIGHT));
 
-    if (logic == symbol::null) {
+    if (logic == symbol::null || logic == "QF_FD") {
         op_names.push_back(builtin_name("bvumul_noovfl",OP_BUMUL_NO_OVFL));
         op_names.push_back(builtin_name("bvsmul_noovfl",OP_BSMUL_NO_OVFL));
         op_names.push_back(builtin_name("bvsmul_noudfl",OP_BSMUL_NO_UDFL));

src/sat/sat_elim_vars.cpp

@@ -302,17 +302,16 @@ namespace sat{
     }
 
     bdd elim_vars::make_clauses(clause_use_list & occs) {
-        bdd result = m.mk_true();
+        bdd result = m.mk_true();       
-        clause_use_list::iterator it = occs.mk_iterator();
+        for (auto it = occs.mk_iterator(); !it.at_end(); it.next()) {
-        while (!it.at_end()) {
             clause const& c = it.curr();
-            if (c.is_blocked()) continue;
+            if (!c.is_blocked()) {
-            bdd cl = m.mk_false();
+                bdd cl = m.mk_false();
-            for (literal l : c) {
+                for (literal l : c) {
-                cl |= mk_literal(l);
+                    cl |= mk_literal(l);
+                }           
+                result &= cl;
             }
-            it.next();
-            result &= cl;
         }
         return result;
     }

src/sat/sat_simplifier.cpp

@@ -418,8 +418,7 @@ namespace sat {
                                             literal target) {
         if (c1.is_blocked()) return;
         clause_use_list const & cs = m_use_list.get(target);
-        clause_use_list::iterator it = cs.mk_iterator();
+        for (auto it = cs.mk_iterator(); !it.at_end(); it.next()) {
-        while (!it.at_end()) {
             clause & c2 = it.curr();
             CTRACE("resolution_bug", c2.was_removed(), tout << "clause has been removed:\n" << c2 << "\n";);
             SASSERT(!c2.was_removed());
@@ -433,7 +432,6 @@ namespace sat {
                     out_lits.push_back(l);
                 }
             }
-            it.next();
         }
     }
 
@@ -532,7 +530,7 @@ namespace sat {
         if (c1.is_blocked()) return;
         clause_use_list const & cs = m_use_list.get(target);
         clause_use_list::iterator it = cs.mk_iterator();
-        while (!it.at_end()) {
+        for (; !it.at_end(); it.next()) {
             clause & c2 = it.curr();
             SASSERT(!c2.was_removed());
             if (&c2 != &c1 &&
@@ -543,7 +541,6 @@ namespace sat {
                     out.push_back(&c2);
                 }
             }
-            it.next();
         }
     }
 
@@ -652,29 +649,16 @@ namespace sat {
         unsigned new_trail_sz = s.m_trail.size();
         for (unsigned i = old_trail_sz; i < new_trail_sz; i++) {
             literal l = s.m_trail[i];
-            {
+            // put clauses with literals assigned to false back into todo-list
-                // put clauses with literals assigned to false back into todo-list
+            for (auto it = m_use_list.get(~l).mk_iterator(); !it.at_end(); it.next()) {
-                clause_use_list & cs = m_use_list.get(~l);
+                m_sub_todo.insert(it.curr());
-                clause_use_list::iterator it = cs.mk_iterator();
-                while (!it.at_end()) {
-                    clause & c = it.curr();
-                    it.next();
-                    m_sub_todo.insert(c);
-                }
             }
-            {
+            clause_use_list& cs = m_use_list.get(l);
-                // erase satisfied clauses
+            for (auto it = cs.mk_iterator(); !it.at_end(); it.next()) {
-                clause_use_list & cs = m_use_list.get(l);
+                clause & c = it.curr();
-                {
+                remove_clause(c, l);
-                    clause_use_list::iterator it = cs.mk_iterator();
-                    while (!it.at_end()) {
-                        clause & c = it.curr();
-                        it.next();
-                        remove_clause(c, l);
-                    }
-                }
-                cs.reset();
             }
+            cs.reset();            
         }
     }
 
@@ -1338,12 +1322,8 @@ namespace sat {
                 }                
                 if (!found) {
                     IF_VERBOSE(100, verbose_stream() << "bca " << l << " " << l2 << "\n";);
-                    watched w(l2, false);
+                    s.get_wlist(~l).push_back(watched(l2, true));
-                    w.set_blocked();
+                    s.get_wlist(~l2).push_back(watched(l, true));
-                    s.get_wlist(~l).push_back(w);
-                    w = watched(l, false);
-                    w.set_blocked();
-                    s.get_wlist(~l2).push_back(w);
                     ++s.m_num_bca;
                 }
             }
@@ -1473,29 +1453,18 @@ namespace sat {
     void simplifier::collect_clauses(literal l, clause_wrapper_vector & r, bool include_blocked) {
         clause_use_list const & cs = m_use_list.get(l);
         clause_use_list::iterator it = cs.mk_iterator();
-        while (!it.at_end()) {
+        for (; !it.at_end(); it.next()) {
             if (!it.curr().is_blocked() || include_blocked) {
                 r.push_back(clause_wrapper(it.curr()));
                 SASSERT(r.back().size() == it.curr().size());
             }
-            it.next();
         }
 
         watch_list & wlist = get_wlist(~l);
-        if (include_blocked) {
+        for (auto & w : wlist) {
-            for (auto & w : wlist) {
+            if (include_blocked ? w.is_binary_non_learned_clause() : w.is_binary_unblocked_clause()) {
-                if (w.is_binary_non_learned_clause2()) {
+                r.push_back(clause_wrapper(l, w.get_literal()));
-                    r.push_back(clause_wrapper(l, w.get_literal()));
+                SASSERT(r.back().size() == 2);
-                    SASSERT(r.back().size() == 2);
-                }
-            }
-        }
-        else {
-            for (auto & w : wlist) {
-                if (w.is_binary_unblocked_clause()) {
-                    r.push_back(clause_wrapper(l, w.get_literal()));
-                    SASSERT(r.back().size() == 2);
-                }
             }
         }
     }
@@ -1607,8 +1576,7 @@ namespace sat {
        \brief Eliminate the clauses where the variable being eliminated occur.
     */
     void simplifier::remove_clauses(clause_use_list const & cs, literal l) {
-        clause_use_list::iterator it  = cs.mk_iterator();
+        for (auto it = cs.mk_iterator(); !it.at_end(); ) {
-        while (!it.at_end()) {
             clause & c = it.curr();
             it.next();
             SASSERT(c.contains(l));
@@ -1641,22 +1609,14 @@ namespace sat {
 
         unsigned before_lits = num_bin_pos*2 + num_bin_neg*2;
 
-        {
+        for (auto it = pos_occs.mk_iterator(); !it.at_end(); it.next()) {
-            clause_use_list::iterator it = pos_occs.mk_iterator();
+            if (!it.curr().is_blocked())
-            while (!it.at_end()) {
+                before_lits += it.curr().size();
-                if (!it.curr().is_blocked())
-                    before_lits += it.curr().size();
-                it.next();
-            }
         }
 
-        {
+        for (auto it = neg_occs.mk_iterator(); !it.at_end(); it.next()) {
-            clause_use_list::iterator it2 = neg_occs.mk_iterator();
+            if (!it.curr().is_blocked())
-            while (!it2.at_end()) {
+                before_lits += it.curr().size();
-                if (!it2.curr().is_blocked())
-                    before_lits += it2.curr().size();
-                it2.next();
-            }
         }
 
         TRACE("resolution", tout << v << " num_pos: " << num_pos << " neg_pos: " << num_neg << " before_lits: " << before_lits << "\n";);

src/sat/sat_watched.h

@@ -88,7 +88,7 @@ namespace sat {
 
         bool is_binary_unblocked_clause() const { return m_val2 == 0; }
         bool is_binary_learned_clause() const { return is_binary_clause() && is_learned(); }
-        bool is_binary_non_learned_clause2() const { return is_binary_clause() && !is_learned(); }
+        bool is_binary_non_learned_clause() const { return is_binary_clause() && !is_learned(); }
 
         void mark_not_learned() { SASSERT(is_learned()); m_val2 = static_cast<unsigned>(BINARY); SASSERT(!is_learned()); }
         void set_blocked() { SASSERT(is_binary_clause()); SASSERT(!is_learned()); m_val2 |= (1 << 3); }

src/sat/tactic/goal2sat.cpp

@@ -1110,7 +1110,6 @@ struct sat2goal::imp {
             r.assert_expr(m.mk_false());
             return;
         }
-        IF_VERBOSE(1, verbose_stream() << "solver2goal " << s.num_vars() << " " << s.clauses().size() << "\n";);
         init_lit2expr(s, map, mc, r.models_enabled());
         // collect units
         unsigned num_vars = s.num_vars();