diff --git a/src/ast/act_cache.cpp b/src/ast/act_cache.cpp
index 14f0985b4..db3f0f12b 100644
--- a/src/ast/act_cache.cpp
+++ b/src/ast/act_cache.cpp
@@ -73,11 +73,9 @@ void act_cache::init() {
 }
 
 void act_cache::dec_refs() {
-    map::iterator it  = m_table.begin();
-    map::iterator end = m_table.end();
-    for (; it != end; ++it) {
-        m_manager.dec_ref((*it).m_key);
-        m_manager.dec_ref(UNTAG(expr*, (*it).m_value));
+    for (auto & kv : m_table) {
+        m_manager.dec_ref(kv.m_key.first);
+        m_manager.dec_ref(UNTAG(expr*, kv.m_value));
     }
 }
 
@@ -105,18 +103,18 @@ act_cache::~act_cache() {
 void act_cache::del_unused() {
     unsigned sz = m_queue.size();
     while (m_qhead < sz) {
-        expr * k = m_queue[m_qhead];
+        entry_t const& e = m_queue[m_qhead];
         m_qhead++;
-        SASSERT(m_table.contains(k));
-        map::key_value * entry = m_table.find_core(k);
+        SASSERT(m_table.contains(e));
+        map::key_value * entry = m_table.find_core(e);
         SASSERT(entry);
         if (GET_TAG(entry->m_value) == 0) {
             // Key k was never accessed by client code.
             // That is, find(k) was never executed by client code.
             m_unused--;
             expr * v = entry->m_value;
-            m_table.erase(k);
-            m_manager.dec_ref(k);
+            m_table.erase(e);
+            m_manager.dec_ref(e.first);
             m_manager.dec_ref(v);
             break;
         }
@@ -135,12 +133,13 @@ void act_cache::del_unused() {
 /**
    \brief Insert a new entry k -> v into the cache.
 */
-void act_cache::insert(expr * k, expr * v) {
+void act_cache::insert(expr * k, unsigned offset, expr * v) {
     SASSERT(k);
+    entry_t e(k, offset);
     if (m_unused >= m_max_unused)
         del_unused();
     expr * dummy = reinterpret_cast<expr*>(1);
-    map::key_value & entry = m_table.insert_if_not_there(k, dummy);
+    map::key_value & entry = m_table.insert_if_not_there(e, dummy);
 #if 0
     unsigned static counter = 0;
     counter++;
@@ -156,7 +155,7 @@ void act_cache::insert(expr * k, expr * v) {
         m_manager.inc_ref(k);
         m_manager.inc_ref(v);
         entry.m_value = v;
-        m_queue.push_back(k);
+        m_queue.push_back(e);
         m_unused++;
         DEBUG_CODE(expected_tag = 0;); // new entry
     }
@@ -175,7 +174,7 @@ void act_cache::insert(expr * k, expr * v) {
     }
     DEBUG_CODE({
         expr * v2;
-        SASSERT(m_table.find(k, v2));
+        SASSERT(m_table.find(e, v2));
         SASSERT(v == UNTAG(expr*, v2));
         SASSERT(expected_tag == GET_TAG(v2));
     });
@@ -185,8 +184,9 @@ void act_cache::insert(expr * k, expr * v) {
    \brief Search for key k in the cache.
    If entry k -> (v, tag) is found, we set tag to 1.
 */
-expr * act_cache::find(expr * k) {
-    map::key_value * entry = m_table.find_core(k);
+expr * act_cache::find(expr * k, unsigned offset) {
+    entry_t e(k, offset);
+    map::key_value * entry = m_table.find_core(e);
     if (entry == nullptr)
         return nullptr;
     if (GET_TAG(entry->m_value) == 0) {
@@ -196,7 +196,7 @@ expr * act_cache::find(expr * k) {
         m_unused--;
         DEBUG_CODE({
             expr * v;
-            SASSERT(m_table.find(k, v));
+            SASSERT(m_table.find(e, v));
             SASSERT(GET_TAG(v) == 1);
         });
     }
diff --git a/src/ast/act_cache.h b/src/ast/act_cache.h
index 67c5cf050..49b49face 100644
--- a/src/ast/act_cache.h
+++ b/src/ast/act_cache.h
@@ -26,9 +26,15 @@ Notes:
 
 class act_cache {
     ast_manager &        m_manager;
-    typedef cmap<expr*, expr*, obj_ptr_hash<expr>, default_eq<expr*> > map;
+    typedef std::pair<expr*, unsigned> entry_t;
+    struct entry_hash {
+        unsigned operator()(entry_t const& e) const {
+            return e.first->hash() + e.second;
+        }
+    };
+    typedef cmap<entry_t, expr*, entry_hash, default_eq<entry_t> > map;
     map                  m_table;
-    ptr_vector<expr>     m_queue; // recently created queue
+    svector<entry_t>     m_queue; // recently created queue
     unsigned             m_qhead;
     unsigned             m_unused;
     unsigned             m_max_unused;
@@ -42,8 +48,10 @@ public:
     act_cache(ast_manager & m);
     act_cache(ast_manager & m, unsigned max_unused);
     ~act_cache();
-    void insert(expr * k, expr * v);
-    expr * find(expr * k);
+    void insert(expr * k, expr * v) { insert(k, 0, v); }
+    expr * find(expr * k) { return find(k, 0); }
+    void insert(expr * k, unsigned offset, expr * v);
+    expr * find(expr * k, unsigned offset);
     void reset();
     void cleanup();
     unsigned size() const { return m_table.size(); }
diff --git a/src/ast/rewriter/rewriter.cpp b/src/ast/rewriter/rewriter.cpp
index 80b690428..7e646871c 100644
--- a/src/ast/rewriter/rewriter.cpp
+++ b/src/ast/rewriter/rewriter.cpp
@@ -42,7 +42,7 @@ void rewriter_core::del_cache_stack() {
     }
 }
 
-void rewriter_core::cache_result(expr * k, expr * v) {
+void rewriter_core::cache_shifted_result(expr * k, unsigned offset, expr * v) {
 #if 0
     // trace for tracking cache usage
     verbose_stream() << "1 " << k->get_id() << std::endl;
@@ -53,7 +53,7 @@ void rewriter_core::cache_result(expr * k, expr * v) {
 
     SASSERT(m().get_sort(k) == m().get_sort(v));
 
-    m_cache->insert(k, v);
+    m_cache->insert(k, offset, v);
 #if 0
     static unsigned num_cached = 0;
     num_cached ++;
diff --git a/src/ast/rewriter/rewriter.h b/src/ast/rewriter/rewriter.h
index 4195e7de6..d380fa707 100644
--- a/src/ast/rewriter/rewriter.h
+++ b/src/ast/rewriter/rewriter.h
@@ -90,8 +90,10 @@ protected:
     void init_cache_stack();
     void del_cache_stack();
     void reset_cache();
-    void cache_result(expr * k, expr * v);
+    void cache_result(expr * k, expr * v) { cache_shifted_result(k, 0, v); }
+    void cache_shifted_result(expr * k, unsigned offset, expr * v);
     expr * get_cached(expr * k) const { return m_cache->find(k); } 
+    expr * get_cached(expr* k, unsigned offset) const { return m_cache->find(k, offset); }
 
     void cache_result(expr * k, expr * v, proof * pr);
     proof * get_cached_pr(expr * k) const { return static_cast<proof*>(m_cache_pr->find(k)); } 
diff --git a/src/ast/rewriter/rewriter_def.h b/src/ast/rewriter/rewriter_def.h
index dfa0c5467..0eeb1f52f 100644
--- a/src/ast/rewriter/rewriter_def.h
+++ b/src/ast/rewriter/rewriter_def.h
@@ -38,9 +38,10 @@ void rewriter_tpl<Config>::process_var(var * v) {
     if (!ProofGen) {
         // bindings are only used when Proof Generation is not enabled.
         unsigned idx = v->get_idx();
+
         if (idx < m_bindings.size()) {
             unsigned index = m_bindings.size() - idx - 1;
-            var * r = (var*)(m_bindings[index]);
+            expr * r = m_bindings[index];
             if (r != nullptr) {
                 CTRACE("rewriter", v->get_sort() != m().get_sort(r),
                        tout << expr_ref(v, m()) << ":" << sort_ref(v->get_sort(), m()) << " != " << expr_ref(r, m()) << ":" << sort_ref(m().get_sort(r), m());
@@ -50,11 +51,18 @@ void rewriter_tpl<Config>::process_var(var * v) {
                 if (!is_ground(r) && m_shifts[index] != m_bindings.size()) {
 
                     unsigned shift_amount = m_bindings.size() - m_shifts[index];
+                    expr* c = get_cached(r, shift_amount);
+                    if (c) {
+                        result_stack().push_back(c);
+                        set_new_child_flag(v);
+                        return;
+                    }
                     expr_ref tmp(m());
                     m_shifter(r, shift_amount, tmp);
                     result_stack().push_back(tmp);
                     TRACE("rewriter", tout << "shift: " << shift_amount << " idx: " << idx << " --> " << tmp << "\n";
                           display_bindings(tout););
+                    cache_shifted_result(r, shift_amount, tmp);                    
                 }
                 else {
                     result_stack().push_back(r);
@@ -380,7 +388,6 @@ void rewriter_tpl<Config>::process_app(app * t, frame & fr) {
                     TRACE("get_macro", display_bindings(tout););
                     begin_scope();
                     m_num_qvars += num_args;
-                    //m_num_qvars = 0;
                     m_root      = def;
                     push_frame(def, false, RW_UNBOUNDED_DEPTH);
                     return;
@@ -480,7 +487,7 @@ void rewriter_tpl<Config>::process_quantifier(quantifier * q, frame & fr) {
             m_root       = q->get_expr();
             unsigned sz = m_bindings.size();
             for (unsigned i = 0; i < num_decls; i++) {
-                m_bindings.push_back(0);
+                m_bindings.push_back(nullptr);
                 m_shifts.push_back(sz);
             }
         }
diff --git a/src/model/model_evaluator.cpp b/src/model/model_evaluator.cpp
index 415b162b4..53defbc3d 100644
--- a/src/model/model_evaluator.cpp
+++ b/src/model/model_evaluator.cpp
@@ -56,6 +56,8 @@ struct evaluator_cfg : public default_rewriter_cfg {
     bool                            m_cache;
     bool                            m_array_equalities;
     bool                            m_array_as_stores;
+    obj_map<func_decl, expr*>       m_def_cache;
+    expr_ref_vector                 m_pinned;
 
     evaluator_cfg(ast_manager & m, model_core & md, params_ref const & p):
         m(m),
@@ -72,7 +74,8 @@ struct evaluator_cfg : public default_rewriter_cfg {
         m_pb_rw(m),
         m_f_rw(m),
         m_seq_rw(m),
-        m_ar(m) {
+        m_ar(m),
+        m_pinned(m) {
         bool flat = true;
         m_b_rw.set_flat(flat);
         m_a_rw.set_flat(flat);
@@ -202,23 +205,29 @@ struct evaluator_cfg : public default_rewriter_cfg {
                 return BR_REWRITE1;
             }
         }
-#if 0
+#if 1
         if (st == BR_FAILED && num == 0 && m_ar.is_as_array(f) && m_model_completion) {
             func_decl* g = nullptr;
             VERIFY(m_ar.is_as_array(f, g));
             expr* def = nullptr;
             quantifier* q = nullptr;
             proof* def_pr = nullptr;
+            if (m_def_cache.find(g, def)) {
+                result = def;
+                return BR_DONE;
+            }
             if (get_macro(g, def, q, def_pr)) {
                 sort_ref_vector vars(m);
                 svector<symbol> var_names;
                 for (unsigned i = 0; i < g->get_arity(); ++i) {
                     var_names.push_back(symbol(i));
-                    vars.push_back(g->get_domain(g->get_arity() - i - 1));
+                    vars.push_back(g->get_domain(i));
                 }
                 result = m.mk_lambda(vars.size(), vars.c_ptr(), var_names.c_ptr(), def);
                 model_evaluator ev(m_model, m_params);
                 result = ev(result);
+                m_pinned.push_back(result);
+                m_def_cache.insert(g, result);
                 return BR_DONE;
             }
         }