adding ematching engine, fixing seq_unicode

src/ast/euf/CMakeLists.txt

@@ -3,6 +3,7 @@ z3_add_component(euf
     euf_enode.cpp
     euf_etable.cpp
     euf_egraph.cpp
+    euf_mam.cpp
   COMPONENT_DEPENDENCIES
     ast
     util

src/ast/euf/euf_egraph.h

@@ -247,6 +247,8 @@ namespace euf {
         */
         bool are_diseq(enode* a, enode* b) const;
 
+        enode * get_enode_eq_to(func_decl * f, unsigned num_args, enode * const * args) { UNREACHABLE(); return nullptr; }
+
         /**
            \brief Maintain and update cursor into propagated consequences.
            The result of get_literal() is a pair (n, is_eq)
@@ -279,6 +281,11 @@ namespace euf {
         template <typename T>
         void explain_eq(ptr_vector<T>& justifications, enode* a, enode* b);
         enode_vector const& nodes() const { return m_nodes; }
+
+        ast_manager& get_manager() { return m; }
+        bool is_relevant(enode* n) const { return true; } // TODO
+        bool resource_limits_exceeded() const { return false; } // TODO
+
         void invariant();
         void copy_from(egraph const& src, std::function<void*(void*)>& copy_justification);
         struct e_pp {

src/ast/euf/euf_enode.h

@@ -18,6 +18,7 @@ Author:
 #include "util/vector.h"
 #include "util/id_var_list.h"
 #include "util/lbool.h"
+#include "util/approx_set.h"
 #include "ast/ast.h"
 #include "ast/euf/euf_justification.h"
 
@@ -60,6 +61,9 @@ namespace euf {
         th_var_list   m_th_vars;
         justification m_justification;
         unsigned      m_num_args{ 0 };
+        signed char         m_lbl_hash { -1 };  // It is different from -1, if enode is used in a pattern
+        approx_set          m_lbls;
+        approx_set          m_plbls;
         enode* m_args[0];
 
         friend class enode_args;
@@ -138,6 +142,7 @@ namespace euf {
         lbool value() const { return m_value;  }
         unsigned bool_var() const { return m_bool_var; }
         bool is_cgr() const { return this == m_cg; }
+        enode* get_cg() const { return m_cg; }
         bool commutative() const { return m_commutative; }
         void mark_interpreted() { SASSERT(num_args() == 0); m_interpreted = true; }
         bool merge_enabled() const { return m_merge_enabled; }
@@ -183,6 +188,16 @@ namespace euf {
         unsigned get_expr_id() const { return m_expr->get_id(); }
         unsigned get_root_id() const { return m_root->m_expr->get_id(); }
         bool children_are_roots() const;
+        enode* get_next() const { return m_next; }
+
+        bool has_lbl_hash() const { UNREACHABLE(); return false; } // TODO
+        unsigned char get_lbl_hash() const { UNREACHABLE(); return 0; } // TOD0
+        void set_lbl_hash(egraph& e) { UNREACHABLE(); }
+        approx_set & get_lbls() { return m_lbls; }        
+        approx_set & get_plbls() { return m_plbls; }        
+        const approx_set & get_lbls() const { return m_lbls; }        
+        const approx_set & get_plbls() const { return m_plbls; }
+
 
         theory_var get_th_var(theory_id id) const { return m_th_vars.find(id); }
         theory_var get_closest_th_var(theory_id id) const;

src/ast/euf/euf_mam.h

@@ -0,0 +1,66 @@
+/*++
+Copyright (c) 2006 Microsoft Corporation
+
+Module Name:
+
+    euf_mam.h
+
+Abstract:
+
+    Matching Abstract Machine
+
+Author:
+
+    Leonardo de Moura (leonardo) 2007-02-13.
+    Nikolaj Bjorner (nbjorner) 2021-01-22.
+
+--*/
+#pragma once
+
+#include "ast/ast.h"
+#include "ast/euf/euf_egraph.h"
+#include <functional>
+
+namespace euf {
+
+    /**
+       \brief Matching Abstract Machine (MAM)
+    */
+    class mam {
+        friend class mam_impl;
+
+        mam() {}
+
+    public:
+
+        static mam * mk(egraph & ctx, 
+                        std::function<void(quantifier*, app*, unsigned, enode* const*, unsigned)>& add_instance);
+        
+        virtual ~mam() {}
+        
+        virtual void add_pattern(quantifier * q, app * mp) = 0;
+
+        virtual void push_scope() = 0;
+
+        virtual void pop_scope(unsigned num_scopes) = 0;
+
+        virtual void match() = 0;
+        
+        virtual void rematch(bool use_irrelevant = false) = 0;
+
+        virtual bool has_work() const = 0;
+        
+        virtual void add_eq_eh(enode * r1, enode * r2) = 0;
+
+        virtual void reset() = 0;
+
+        virtual std::ostream& display(std::ostream& out) = 0;
+        
+        virtual void on_match(quantifier * q, app * pat, unsigned num_bindings, enode * const * bindings, unsigned max_generation) = 0;
+        
+        virtual bool is_shared(enode * n) const = 0;
+
+        virtual bool check_missing_instances() = 0;
+    };
+};
+

src/sat/smt/q_solver.cpp

@@ -3,7 +3,7 @@ Copyright (c) 2020 Microsoft Corporation
 
 Module Name:
 
-    a_solver.cpp
+    q_solver.cpp
 
 Abstract:
 
@@ -15,18 +15,21 @@ Author:
 
 --*/
 
+#include "ast/ast_util.h"
+#include "ast/well_sorted.h"
 #include "ast/rewriter/var_subst.h"
+#include "ast/normal_forms/pull_quant.h"
 #include "sat/smt/q_solver.h"
 #include "sat/smt/euf_solver.h"
 #include "sat/smt/sat_th.h"
-#include "ast/normal_forms/pull_quant.h"
-#include "ast/well_sorted.h"
+
 
 namespace q {
 
     solver::solver(euf::solver& ctx, family_id fid) :
         th_euf_solver(ctx, ctx.get_manager().get_family_name(fid), fid),
-        m_mbqi(ctx,  *this)
+        m_mbqi(ctx,  *this),
+        m_expanded(ctx.get_manager())
     {
     }
 
@@ -34,12 +37,19 @@ namespace q {
         expr* e = bool_var2expr(l.var());
         if (!is_forall(e) && !is_exists(e))
             return;
-        if (l.sign() == is_forall(e)) 
-            add_clause(~l, skolemize(to_quantifier(e)));        
-        else {            
-            // add_clause(~l, specialize(to_quantifier(e)));
-            ctx.push_vec(m_universal, l);
+        quantifier* q = to_quantifier(e);
+
+        auto const& exp = expand(q);
+        if (exp.size() > 1) {
+            for (expr* e : exp) 
+                add_clause(~l, ctx.internalize(e, l.sign(), false, false));                    
+            return;
         }
+
+        if (l.sign() == is_forall(e)) 
+            add_clause(~l, skolemize(q));
+        else 
+            ctx.push_vec(m_universal, l);
         m_stats.m_num_quantifier_asserts++;
     }
 
@@ -204,4 +214,26 @@ namespace q {
         return g;
     }
 
+    expr_ref_vector const& solver::expand(quantifier* q) {
+        m_expanded.reset();
+        if (is_forall(q)) 
+            flatten_and(q->get_expr(), m_expanded);
+        else if (is_exists(q)) 
+            flatten_or(q->get_expr(), m_expanded);
+        else
+            UNREACHABLE();
+
+        if (m_expanded.size() > 1) {
+            for (unsigned i = m_expanded.size(); i-- > 0; ) {
+                expr_ref tmp(m.update_quantifier(q, m_expanded.get(i)), m);
+                ctx.get_rewriter()(tmp);
+                m_expanded[i] = tmp;
+            }
+            return m_expanded;
+        }
+        m_expanded.reset();
+        m_expanded.push_back(q);
+        return m_expanded;
+    }
+
 }

src/sat/smt/q_solver.h

@@ -3,7 +3,7 @@ Copyright (c) 2020 Microsoft Corporation
 
 Module Name:
 
-    a_solver.h
+    q_solver.h
 
 Abstract:
 
@@ -45,12 +45,15 @@ namespace q {
         sat::literal_vector    m_universal;
         obj_map<sort, expr*>   m_unit_table;
         mutable ptr_vector<expr> m_todo;
+        expr_ref_vector        m_expanded;
 
         sat::literal instantiate(quantifier* q, bool negate, std::function<expr* (quantifier*, unsigned)>& mk_var);
         sat::literal skolemize(quantifier* q);
         sat::literal specialize(quantifier* q);
         void init_units();
         expr* get_unit(sort* s);
+        
+        expr_ref_vector const& expand(quantifier* q);
 
     public:
 

src/smt/seq_unicode.cpp

@@ -27,6 +27,7 @@ namespace smt {
         m_bb(m, ctx().get_fparams())
     {
         m_enabled = gparams::get_value("unicode") == "true";
+        m_bits2char = symbol("bits2char");
     }
 
     struct seq_unicode::reset_bits : public trail<context> {
@@ -48,24 +49,52 @@ namespace smt {
         return (m_bits.size() > (unsigned)v) && !m_bits[v].empty();
     }
 
+    /**
+     * Initialize bits associated with theory variable v.
+     * add also the equality bits2char(char2bit(e, 0),..., char2bit(e, 15)) = e
+     * to have congruence closure propagate equalities when the bits of two vectors
+     * end up having the same values. This, together with congruence closure over char2bit 
+     * should ensure that two characters have the same bit-vector assignments if and only
+     * if they are equal. Nevertheless, the code also checks for these constraints
+     * independently and adds Ackerman axioms on demand.
+     */
+
     void seq_unicode::init_bits(theory_var v) {
         if (has_bits(v))
             return;
+
+        expr* e = th.get_expr(v);
         m_bits.reserve(v + 1);
         auto& bits = m_bits[v];
-        expr* e = th.get_expr(v);
         while ((unsigned) v >= m_ebits.size())
             m_ebits.push_back(expr_ref_vector(m));
+        
         ctx().push_trail(reset_bits(*this, v));
         auto& ebits = m_ebits[v];
         SASSERT(ebits.empty());
-        for (unsigned i = 0; i < zstring::num_bits(); ++i) 
-            ebits.push_back(seq.mk_char_bit(e, i));
-        ctx().internalize(ebits.c_ptr(), ebits.size(), true);
-        for (expr* arg : ebits)
-            bits.push_back(literal(ctx().get_bool_var(arg)));            
-        for (literal bit : bits)
-            ctx().mark_as_relevant(bit);
+
+        bool is_bits2char = seq.is_skolem(e) && to_app(e)->get_decl()->get_parameter(0).get_symbol() == m_bits2char;
+        if (is_bits2char) {
+            for (expr* arg : *to_app(e)) {
+                ebits.push_back(arg);
+                bits.push_back(literal(ctx().get_bool_var(arg)));
+            }            
+        }
+        else {            
+            for (unsigned i = 0; i < zstring::num_bits(); ++i) 
+                ebits.push_back(seq.mk_char_bit(e, i));
+            ctx().internalize(ebits.c_ptr(), ebits.size(), true);
+            for (expr* arg : ebits)
+                bits.push_back(literal(ctx().get_bool_var(arg)));            
+            for (literal bit : bits)
+                ctx().mark_as_relevant(bit);
+            expr_ref bits2char(seq.mk_skolem(m_bits2char, ebits.size(), ebits.c_ptr(), m.get_sort(e)), m);
+            ctx().mark_as_relevant(bits2char);
+            enode* n1 = th.ensure_enode(e);
+            enode* n2 = th.ensure_enode(bits2char);
+            justification* j = ctx().mk_justification(ext_theory_eq_propagation_justification(th.get_id(), ctx().get_region(), 0, nullptr, 0, nullptr, n1, n2));
+            ctx().assign_eq(n1, n2, eq_justification(j));
+        }
         ++m_stats.m_num_blast;
     }
 
@@ -74,6 +103,8 @@ namespace smt {
         VERIFY(seq.is_char_le(term, x, y));
         theory_var v1 = ctx().get_enode(x)->get_th_var(th.get_id());
         theory_var v2 = ctx().get_enode(y)->get_th_var(th.get_id());
+        init_bits(v1);
+        init_bits(v2);
         auto const& b1 = get_ebits(v1);
         auto const& b2 = get_ebits(v2);
         expr_ref e(m);
@@ -232,6 +263,7 @@ namespace smt {
         enode* n = th.ensure_enode(seq.mk_char(zstring::max_char()));
         theory_var w = n->get_th_var(th.get_id());                    
         SASSERT(has_bits(w));
+        init_bits(v);
         auto const& mbits = get_ebits(w);
         auto const& bits = get_ebits(v);
         expr_ref le(m);
@@ -247,6 +279,8 @@ namespace smt {
         literal eq = th.mk_literal(m.mk_eq(th.get_expr(v), th.get_expr(w)));
         ctx().mark_as_relevant(eq);
         literal_vector lits;
+        init_bits(v);
+        init_bits(w);
         auto& a = get_ebits(v);
         auto& b = get_ebits(w);
         for (unsigned i = a.size(); i-- > 0; ) {

src/smt/seq_unicode.h

@@ -44,6 +44,7 @@ namespace smt {
         bool             m_enabled { false };
         bit_blaster      m_bb;
         stats            m_stats;
+        symbol           m_bits2char;
 
         struct reset_bits;
 

src/util/parray.h

@@ -66,13 +66,13 @@ private:
             value * m_values;
         };
 
-        ckind kind() const { return static_cast<ckind>(m_kind); }
+        enum ckind kind() const { return static_cast<enum ckind>(m_kind); }
 
         unsigned idx() const { SASSERT(kind() != ROOT); return m_idx; }
         unsigned size() const { SASSERT(kind() == ROOT); return m_size; }
         cell * next() const { SASSERT(kind() != ROOT); return m_next; }
         value const & elem() const { SASSERT(kind() == SET || kind() == PUSH_BACK); return m_elem; }
-        cell(ckind k):m_ref_count(1), m_kind(k), m_size(0), m_values(nullptr) {}
+        cell(enum ckind k):m_ref_count(1), m_kind(k), m_size(0), m_values(nullptr) {}
     };
 
     value_manager &  m_vmanager;