add array selects to basic ackerman reduction improves performance significantly for #2525 as it now uses the SAT solver core instead of SMT core

Signed-off-by: Nikolaj Bjorner <[email protected]>

Author: NikolajBjorner

src/ackermannization/ackermannize_bv_model_converter.cpp

@@ -18,5 +18,5 @@
 #include "ackermannization/ackermannize_bv_model_converter.h"
 
 model_converter * mk_ackermannize_bv_model_converter(ast_manager & m, const ackr_info_ref& info) {
- return mk_ackr_model_converter(m, info);
+    return mk_ackr_model_converter(m, info);
 }

src/ackermannization/ackr_bound_probe.cpp

@@ -14,42 +14,67 @@
 
  Revision History:
 --*/
+#include "ast/array_decl_plugin.h"
+#include "ast/ast_smt2_pp.h"
 #include "ackermannization/ackr_helper.h"
 #include "ackermannization/ackr_bound_probe.h"
-#include "ast/ast_smt2_pp.h"
 
 /*
   For each function f, calculate the number of its occurrences o_f and compute "o_f choose 2".
   The probe then sums up these for all functions.
   This upper bound might be crude because some congruence lemmas trivially simplify to true.
 */
 class ackr_bound_probe : public probe {
+
     struct proc {
         typedef ackr_helper::fun2terms_map fun2terms_map;
+        typedef ackr_helper::sel2terms_map sel2terms_map;
         typedef ackr_helper::app_set       app_set;
-        ast_manager&                 m_m;
+        ast_manager&                 m;
         fun2terms_map                m_fun2terms; // a map from functions to occurrences
+        sel2terms_map                m_sel2terms; // a map from functions to occurrences
         ackr_helper                  m_ackr_helper;
+        expr_mark                    m_non_select;
 
-        proc(ast_manager & m) : m_m(m), m_ackr_helper(m) { }
+        proc(ast_manager & m) : m(m), m_ackr_helper(m) { }
 
         ~proc() {
-            fun2terms_map::iterator it = m_fun2terms.begin();
-            const fun2terms_map::iterator end = m_fun2terms.end();
-            for (; it != end; ++it) dealloc(it->get_value());
+            for (auto & kv : m_fun2terms) {
+                dealloc(kv.m_value);
+            }
+            for (auto & kv : m_sel2terms) {
+                dealloc(kv.m_value);
+            }
+        }
+
+        void prune_non_select() {
+            m_ackr_helper.prune_non_select(m_sel2terms, m_non_select);
         }
 
         void operator()(quantifier *) {}
         void operator()(var *) {}
         void operator()(app * a) {
             if (a->get_num_args() == 0) return;
-            if (!m_ackr_helper.should_ackermannize(a)) return;
-            func_decl* const fd = a->get_decl();
+            m_ackr_helper.mark_non_select(a, m_non_select);
             app_set* ts = nullptr;
-            if (!m_fun2terms.find(fd, ts)) {
-                ts = alloc(app_set);
-                m_fun2terms.insert(fd, ts);
+            if (m_ackr_helper.is_select(a)) {
+                app* sel = to_app(a->get_arg(0));
+                if (!m_sel2terms.find(sel, ts)) {
+                    ts = alloc(app_set);
+                    m_sel2terms.insert(sel, ts);
+                }
+            }
+            else if (m_ackr_helper.is_uninterp_fn(a)) {
+                func_decl* const fd = a->get_decl();
+                if (!m_fun2terms.find(fd, ts)) {
+                    ts = alloc(app_set);
+                    m_fun2terms.insert(fd, ts);
+                }
+            }
+            else {
+                return;
             }
+            
             ts->insert(a);
         }
     };
@@ -64,7 +89,8 @@ class ackr_bound_probe : public probe {
         for (unsigned i = 0; i < sz; i++) {
             for_each_expr_core<proc, expr_fast_mark1, true, true>(p, visited, g.form(i));
         }
-        const double total = ackr_helper::calculate_lemma_bound(p.m_fun2terms);
+        p.prune_non_select();
+        double total = ackr_helper::calculate_lemma_bound(p.m_fun2terms, p.m_sel2terms);
         TRACE("ackermannize", tout << "total=" << total << std::endl;);
         return result(total);
     }

src/ackermannization/ackr_helper.cpp

@@ -16,14 +16,13 @@
 --*/
 #include "ackermannization/ackr_helper.h"
 
-double ackr_helper::calculate_lemma_bound(ackr_helper::fun2terms_map& occurrences) {
-    fun2terms_map::iterator it = occurrences.begin();
-    const fun2terms_map::iterator end = occurrences.end();
+double ackr_helper::calculate_lemma_bound(fun2terms_map const& occs1, sel2terms_map const& occs2) {
     double total = 0;
-    for (; it != end; ++it) {
-        const unsigned fsz = it->m_value->size();
-        const double n2 = n_choose_2_chk(fsz);
-        total += n2;
+    for (auto const& kv : occs1) {
+        total += n_choose_2_chk(kv.m_value->size());
+    }
+    for (auto const& kv : occs2) {
+        total += n_choose_2_chk(kv.m_value->size());
     }
     return total;
 }

src/ackermannization/ackr_helper.h

@@ -18,45 +18,86 @@
 #define ACKR_HELPER_H_
 
 #include "ast/bv_decl_plugin.h"
+#include "ast/array_decl_plugin.h"
 
 class ackr_helper {
-    public:
-        typedef obj_hashtable<app>           app_set;
-        typedef obj_map<func_decl, app_set*> fun2terms_map;
-
-        ackr_helper(ast_manager& m) : m_bvutil(m) {}
-
-        /**
-        \brief  Determines if a given function should be Ackermannized.
-
-         This includes all uninterpreted functions but also "special" functions, e.g. OP_BSMOD0,
-         which are not marked as uninterpreted but effectively are.
-        */
-        inline bool should_ackermannize(app const * a) const {
-            if (is_uninterp(a))
-                return true;
-            else {
-                decl_plugin * p = m_bvutil.get_manager().get_plugin(a->get_family_id());
-                return p->is_considered_uninterpreted(a->get_decl());
+public:
+    typedef obj_hashtable<app>           app_set;
+    typedef obj_map<func_decl, app_set*> fun2terms_map;
+    typedef obj_map<app, app_set*>      sel2terms_map;
+    
+    ackr_helper(ast_manager& m) : m_bvutil(m), m_autil(m) {}
+    
+    /**
+       \brief  Determines if a given function should be Ackermannized.
+       
+       This includes all uninterpreted functions but also "special" functions, e.g. OP_BSMOD0,
+       which are not marked as uninterpreted but effectively are.
+    */
+    inline bool is_uninterp_fn(app const * a) const {
+        if (is_uninterp(a))
+            return true;
+        else {
+            decl_plugin * p = m_bvutil.get_manager().get_plugin(a->get_family_id());
+            return p->is_considered_uninterpreted(a->get_decl());
+        }
+    }
+
+    /**
+       \brief determines if a term is a candidate select for Ackerman reduction
+    */
+    inline bool is_select(app* a) {
+        return m_autil.is_select(a) && is_uninterp_const(a->get_arg(0));
+    }
+
+    void mark_non_select(app* a, expr_mark& non_select) {
+        if (m_autil.is_select(a)) {
+            bool first = true;
+            for (expr* arg : *a) {
+                if (first) 
+                    first = false; 
+                else 
+                    non_select.mark(arg, true);
             }
         }
-
-        inline bv_util& bvutil() { return m_bvutil; }
-
-        /**
-        \brief Calculates an upper bound for congruence lemmas given a map of function of occurrences.
-        */
-        static double calculate_lemma_bound(fun2terms_map& occurrences);
-
-        /** \brief Calculate n choose 2. **/
-        inline static unsigned n_choose_2(unsigned n) { return n & 1 ? (n * (n >> 1)) : (n >> 1) * (n - 1); }
-
-        /** \brief Calculate n choose 2 guarded for overflow. Returns infinity if unsafe. **/
-        inline static double n_choose_2_chk(unsigned n) {
-            SASSERT(std::numeric_limits<unsigned>().max() & 32);
-            return n & (1 << 16) ? std::numeric_limits<double>().infinity() : n_choose_2(n);
+        else {
+            for (expr* arg : *a) {
+                non_select.mark(arg, true);
+            }
+        }
+    }
+
+    void prune_non_select(obj_map<app, app_set*> & sels, expr_mark& non_select) {
+        ptr_vector<app> nons;
+        for (auto& kv : sels) {
+            if (non_select.is_marked(kv.m_key)) {
+                nons.push_back(kv.m_key);
+                dealloc(kv.m_value);
+            }
+        }
+        for (app* s : nons) {
+            sels.erase(s);
         }
-    private:
-        bv_util                              m_bvutil;
+    }
+    
+    inline bv_util& bvutil() { return m_bvutil; }
+    
+    /**
+       \brief Calculates an upper bound for congruence lemmas given a map of function of occurrences.
+    */
+    static double calculate_lemma_bound(fun2terms_map const& occs1, sel2terms_map const& occs2);
+    
+    /** \brief Calculate n choose 2. **/
+    inline static unsigned n_choose_2(unsigned n) { return n & 1 ? (n * (n >> 1)) : (n >> 1) * (n - 1); }
+    
+    /** \brief Calculate n choose 2 guarded for overflow. Returns infinity if unsafe. **/
+    inline static double n_choose_2_chk(unsigned n) {
+        SASSERT(std::numeric_limits<unsigned>().max() & 32);
+        return n & (1 << 16) ? std::numeric_limits<double>().infinity() : n_choose_2(n);
+    }
+    
+private:
+    bv_util                              m_bvutil;
+    array_util                           m_autil;
 };
-#endif /* ACKR_HELPER_H_6475 */
+#endif /* ACKR_HELPER_H_ */

src/ackermannization/ackr_info.h

@@ -16,9 +16,9 @@ Revision History:
 #ifndef ACKR_INFO_H_
 #define ACKR_INFO_H_
 
+#include "util/ref.h"
 #include "util/obj_hashtable.h"
 #include "ast/ast.h"
-#include "util/ref.h"
 #include "ast/rewriter/expr_replacer.h"
 #include "ast/ast_translation.h"
 
@@ -34,18 +34,18 @@ Revision History:
 **/
 class ackr_info {
     public:
-        ackr_info(ast_manager& m)
-        : m_m(m)
-        , m_er(mk_default_expr_replacer(m))
-        , m_subst(m_m)
-        , m_ref_count(0)
-        , m_sealed(false)
+        ackr_info(ast_manager& m) : 
+            m(m),
+            m_er(mk_default_expr_replacer(m)),
+            m_subst(m),
+            m_ref_count(0),
+            m_sealed(false)
         {}
 
         virtual ~ackr_info() {
-            for (t2ct::iterator i = m_t2c.begin(); i != m_t2c.end(); ++i) {
-                m_m.dec_ref(i->m_key);
-                m_m.dec_ref(i->m_value);
+            for (auto & kv : m_t2c) {
+                m.dec_ref(kv.m_key);
+                m.dec_ref(kv.m_value);
             }
         }
 
@@ -55,13 +55,15 @@ class ackr_info {
             m_t2c.insert(term,c);
             m_c2t.insert(c->get_decl(),term);
             m_subst.insert(term, c);
-            m_m.inc_ref(term);
-            m_m.inc_ref(c);
+            m.inc_ref(term);
+            m.inc_ref(c);
         }
 
-        inline void abstract(expr * e, expr_ref& res) {
+        inline expr_ref abstract(expr * e) {
+            expr_ref res(m);
             SASSERT(m_sealed);
             (*m_er)(e, res);
+            return res;
         }
 
         inline app* find_term(func_decl* c)  const {
@@ -71,22 +73,18 @@ class ackr_info {
         }
 
         inline app* get_abstr(app* term)  const {
-            app * const rv = m_t2c.find(term);
-            SASSERT(rv);
-            return rv;
+            return m_t2c.find(term);
         }
 
         inline void seal() {
-            m_sealed=true;
+            m_sealed = true;
             m_er->set_substitution(&m_subst);
         }
 
         virtual ackr_info * translate(ast_translation & translator) {
             ackr_info * const retv = alloc(ackr_info, translator.to());
-            for (t2ct::iterator i = m_t2c.begin(); i != m_t2c.end(); ++i) {
-                app * const k = translator(i->m_key);
-                app * const v = translator(i->m_value);
-                retv->set_abstr(k, v);
+            for (auto & kv : m_t2c) {
+                retv->set_abstr(translator(kv.m_key), translator(kv.m_value));
             }
             if (m_sealed) retv->seal();
             return retv;
@@ -102,10 +100,11 @@ class ackr_info {
                 dealloc(this);
             }
         }
+
     private:
         typedef obj_map<app, app*> t2ct;
         typedef obj_map<func_decl, app*> c2tt;
-        ast_manager& m_m;
+        ast_manager& m;
 
         t2ct m_t2c; // terms to constants
         c2tt m_c2t; // constants to terms (inversion of m_t2c)