Source

z3 / src / ast / rewriter / th_rewriter.cpp

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/*++
Copyright (c) 2011 Microsoft Corporation

Module Name:

    th_rewriter.h

Abstract:

    Rewriter for applying all builtin (cheap) theory rewrite rules.

Author:

    Leonardo (leonardo) 2011-04-07

Notes:

--*/
#include"th_rewriter.h"
#include"bool_rewriter.h"
#include"arith_rewriter.h"
#include"bv_rewriter.h"
#include"datatype_rewriter.h"
#include"array_rewriter.h"
#include"float_rewriter.h"
#include"dl_rewriter.h"
#include"rewriter_def.h"
#include"expr_substitution.h"
#include"ast_smt2_pp.h"
#include"cooperate.h"
#include"var_subst.h"
#include"ast_util.h"
#include"well_sorted.h"

struct th_rewriter_cfg : public default_rewriter_cfg {
    bool_rewriter       m_b_rw;
    arith_rewriter      m_a_rw;
    bv_rewriter         m_bv_rw;
    array_rewriter      m_ar_rw;
    datatype_rewriter   m_dt_rw;
    float_rewriter      m_f_rw;
    dl_rewriter         m_dl_rw;
    arith_util          m_a_util;
    bv_util             m_bv_util;
    unsigned long long  m_max_memory; // in bytes
    unsigned            m_max_steps;
    bool                m_pull_cheap_ite;
    bool                m_flat;
    bool                m_cache_all;
    bool                m_push_ite_arith;
    bool                m_push_ite_bv;

    // substitution support
    expr_dependency_ref m_used_dependencies; // set of dependencies of used substitutions
    expr_substitution * m_subst;

    ast_manager & m() const { return m_b_rw.m(); }

    void updt_local_params(params_ref const & p) {
        m_flat           = p.get_bool(":flat", true);
        m_max_memory     = megabytes_to_bytes(p.get_uint(":max-memory", UINT_MAX));
        m_max_steps      = p.get_uint(":max-steps", UINT_MAX);
        m_pull_cheap_ite = p.get_bool(":pull-cheap-ite", false);
        m_cache_all      = p.get_bool(":cache-all", false);
        m_push_ite_arith = p.get_bool(":push-ite-arith", false);
        m_push_ite_bv    = p.get_bool(":push-ite-bv", false);
    }
        
    void updt_params(params_ref const & p) {
        m_b_rw.updt_params(p);
        m_a_rw.updt_params(p);
        m_bv_rw.updt_params(p);
        m_ar_rw.updt_params(p);
        updt_local_params(p);
    }

    bool flat_assoc(func_decl * f) const { 
        if (!m_flat) return false;
        family_id fid = f->get_family_id();
        if (fid == null_family_id)
            return false;
        decl_kind k   = f->get_decl_kind();
        if (fid == m_b_rw.get_fid())
            return k == OP_AND || k == OP_OR;
        if (fid == m_a_rw.get_fid())
            return k == OP_ADD;
        if (fid == m_bv_rw.get_fid())
            return k == OP_BADD || k == OP_BOR || k == OP_BAND || k == OP_BXOR;
        return false;
    }

    bool rewrite_patterns() const { return false; }
    
    bool cache_all_results() const { return m_cache_all; }

    bool max_steps_exceeded(unsigned num_steps) const { 
        cooperate("simplifier");
        if (memory::get_allocation_size() > m_max_memory)
            throw rewriter_exception(Z3_MAX_MEMORY_MSG);
        return num_steps > m_max_steps;
    }

    // Return true if t is of the form
    //    (= t #b0)
    //    (= t #b1)
    //    (= #b0 t)
    //    (= #b1 t)
    bool is_eq_bit(expr * t, expr * & x, unsigned & val) {
        if (!m().is_eq(t))
            return false;
        expr * lhs = to_app(t)->get_arg(0);
        if (!m_bv_rw.is_bv(lhs))
            return false;
        if (m_bv_rw.get_bv_size(lhs) != 1)
            return false;
        expr * rhs = to_app(t)->get_arg(1);
        rational v;
        unsigned sz;
        if (m_bv_rw.is_numeral(lhs, v, sz)) {
            x    = rhs;
            val  = v.get_unsigned();
            SASSERT(val == 0 || val == 1);
            return true;
        }
        if (m_bv_rw.is_numeral(rhs, v, sz)) {
            x   = lhs;
            val  = v.get_unsigned();
            SASSERT(val == 0 || val == 1);
            return true;
        }
        return false;
    }

    // (iff (= x bit1) A)
    // --->
    // (= x (ite A bit1 bit0))
    br_status apply_tamagotchi(expr * lhs, expr * rhs, expr_ref & result) {
        expr * x;
        unsigned val;
        if (is_eq_bit(lhs, x, val)) {
            result = m().mk_eq(x, m().mk_ite(rhs, m_bv_rw.mk_numeral(val, 1), m_bv_rw.mk_numeral(1-val, 1)));
            return BR_REWRITE2;
        }
        if (is_eq_bit(rhs, x, val)) {
            result = m().mk_eq(x, m().mk_ite(lhs, m_bv_rw.mk_numeral(val, 1), m_bv_rw.mk_numeral(1-val, 1)));
            return BR_REWRITE2;
        }
        return BR_FAILED;
    }

    br_status reduce_app_core(func_decl * f, unsigned num, expr * const * args, expr_ref & result) {
        family_id fid = f->get_family_id();
        if (fid == null_family_id)
            return BR_FAILED;
        br_status st = BR_FAILED;
        if (fid == m_b_rw.get_fid()) {
            decl_kind k = f->get_decl_kind();
            if (k == OP_EQ) {
                // theory dispatch for =
                SASSERT(num == 2);
                family_id s_fid = m().get_sort(args[0])->get_family_id();
                if (s_fid == m_a_rw.get_fid())
                    st = m_a_rw.mk_eq_core(args[0], args[1], result);
                else if (s_fid == m_bv_rw.get_fid())
                    st = m_bv_rw.mk_eq_core(args[0], args[1], result);
                else if (s_fid == m_dt_rw.get_fid())
                    st = m_dt_rw.mk_eq_core(args[0], args[1], result);
                else if (s_fid == m_f_rw.get_fid())
                    st = m_f_rw.mk_eq_core(args[0], args[1], result);

                if (st != BR_FAILED)
                    return st;
            }
            if (k == OP_EQ || k == OP_IFF) {
                SASSERT(num == 2);
                st = apply_tamagotchi(args[0], args[1], result);            
                if (st != BR_FAILED)
                    return st;
            }
            return m_b_rw.mk_app_core(f, num, args, result);
        }
        if (fid == m_a_rw.get_fid())
            return m_a_rw.mk_app_core(f, num, args, result);
        if (fid == m_bv_rw.get_fid())
            return m_bv_rw.mk_app_core(f, num, args, result);
        if (fid == m_ar_rw.get_fid())
            return m_ar_rw.mk_app_core(f, num, args, result);
        if (fid == m_dt_rw.get_fid())
            return m_dt_rw.mk_app_core(f, num, args, result);
        if (fid == m_f_rw.get_fid())
            return m_f_rw.mk_app_core(f, num, args, result);
        if (fid == m_dl_rw.get_fid())
            return m_dl_rw.mk_app_core(f, num, args, result);
        return BR_FAILED;
    }

    // auxiliary function for pull_ite_core
    expr * mk_eq_value(expr * lhs, expr * value) {
        SASSERT(m().is_value(value));
        if (m().is_value(lhs)) {
            return lhs == value ? m().mk_true() : m().mk_false();
        }
        return m().mk_eq(lhs, value);
    }

    template<bool SWAP>
    br_status pull_ite_core(func_decl * p, app * ite, app * value, expr_ref & result) {
        if (m().is_eq(p)) {
            result = m().mk_ite(ite->get_arg(0),
                                mk_eq_value(ite->get_arg(1), value),
                                mk_eq_value(ite->get_arg(2), value));
            return BR_REWRITE2;
        }
        else {
            if (SWAP) {
                result = m().mk_ite(ite->get_arg(0), 
                                    m().mk_app(p, value, ite->get_arg(1)),
                                    m().mk_app(p, value, ite->get_arg(2)));
                return BR_REWRITE2;
            }
            else {
                result = m().mk_ite(ite->get_arg(0), 
                                    m().mk_app(p, ite->get_arg(1), value),
                                    m().mk_app(p, ite->get_arg(2), value));
                return BR_REWRITE2;
            }
        }
    }

    // Return true if t is an ite-value-tree form defined as:
    //    ite-value-tree := (ite c <subtree> <subtree>)
    //    subtree        := value
    //                   |  (ite c <subtree> <subtree>)
    //    
    bool is_ite_value_tree(expr * t) {
        if (!m().is_ite(t))
            return false;
        ptr_buffer<app> todo;
        todo.push_back(to_app(t));
        while (!todo.empty()) {
            app * ite = todo.back();
            todo.pop_back();
            expr * arg1 = ite->get_arg(1);
            expr * arg2 = ite->get_arg(2);

            if (m().is_ite(arg1) && arg1->get_ref_count() == 1) // do not apply on shared terms, since it may blowup
                todo.push_back(to_app(arg1));
            else if (!m().is_value(arg1))
                return false;

            if (m().is_ite(arg2) && arg2->get_ref_count() == 1) // do not apply on shared terms, since it may blowup
                todo.push_back(to_app(arg2));
            else if (!m().is_value(arg2))
                return false;
        }
        return true;
    }
    
    br_status pull_ite(func_decl * f, unsigned num, expr * const * args, expr_ref & result) {
        if (num == 2 && m().is_bool(f->get_range()) && !m().is_bool(args[0])) {
            if (m().is_ite(args[0])) {
                if (m().is_value(args[1]))
                    return pull_ite_core<false>(f, to_app(args[0]), to_app(args[1]), result);
                if (m().is_ite(args[1]) && to_app(args[0])->get_arg(0) == to_app(args[1])->get_arg(0)) {
                    // (p (ite C A1 B1) (ite C A2 B2)) --> (ite (p A1 A2) (p B1 B2))
                    result = m().mk_ite(to_app(args[0])->get_arg(0),
                                        m().mk_app(f, to_app(args[0])->get_arg(1), to_app(args[1])->get_arg(1)),
                                        m().mk_app(f, to_app(args[0])->get_arg(2), to_app(args[1])->get_arg(2)));
                    return BR_REWRITE2;
                }
            }
            if (m().is_ite(args[1]) && m().is_value(args[0]))
                return pull_ite_core<true>(f, to_app(args[1]), to_app(args[0]), result);
        }
        family_id fid = f->get_family_id();
        if (num == 2 && (fid == m().get_basic_family_id() || fid == m_a_rw.get_fid() || fid == m_bv_rw.get_fid())) {
            // (f v3 (ite c v1 v2)) --> (ite v (f v3 v1) (f v3 v2))
            if (m().is_value(args[0]) && is_ite_value_tree(args[1]))
                return pull_ite_core<true>(f, to_app(args[1]), to_app(args[0]), result);

            // (f (ite c v1 v2) v3) --> (ite v (f v1 v3) (f v2 v3))
            if (m().is_value(args[1]) && is_ite_value_tree(args[0]))
                return pull_ite_core<false>(f, to_app(args[0]), to_app(args[1]), result);
        }
        return BR_FAILED;
    }

    br_status pull_ite(expr_ref & result) {
        expr * t = result.get();
        if (is_app(t)) {
            br_status st = pull_ite(to_app(t)->get_decl(), to_app(t)->get_num_args(), to_app(t)->get_args(), result);
            if (st != BR_FAILED)
                return st;
        }
        return BR_DONE;
    }

    bool is_arith_bv_app(expr * t) const {
        if (!is_app(t))
            return false;
        family_id fid = to_app(t)->get_family_id();
        return ((fid == m_a_rw.get_fid() && m_push_ite_arith) || 
                (fid == m_bv_rw.get_fid() && m_push_ite_bv));
    }

    bool get_neutral_elem(app * t, expr_ref & n) {
        family_id fid = t->get_family_id();
        if (fid == m_a_rw.get_fid()) {
            switch (t->get_decl_kind()) {
            case OP_ADD: n = m_a_util.mk_numeral(rational(0), m().get_sort(t)); return true;
            case OP_MUL: n = m_a_util.mk_numeral(rational(1), m().get_sort(t)); return true;
            default:
                return false;
            }
        }
        if (fid == m_bv_rw.get_fid()) {
            switch (t->get_decl_kind()) {
            case OP_BADD: n = m_bv_util.mk_numeral(rational(0), m().get_sort(t)); return true;
            case OP_BMUL: n = m_bv_util.mk_numeral(rational(1), m().get_sort(t)); return true;
            default:
                return false;
            }
        }
        return false;
    }
    
    /**
       \brief Try to "unify" t1 and t2
       Examples
         (+ 2 a) (+ 3 a) -->  2, 3, a
         (+ 2 a) a       -->  2, 0, a
         ...
    */
    bool unify_core(app * t1, expr * t2, expr_ref & new_t1, expr_ref & new_t2, expr_ref & c, bool & first) {
        if (t1->get_num_args() != 2)
            return false;
        expr * a1 = t1->get_arg(0);
        expr * b1 = t1->get_arg(1);
        if (t2 == b1) {
            if (get_neutral_elem(t1, new_t2)) {
                new_t1 = a1;
                c      = b1;
                first  = false;
                return true;
            }
        }
        else if (t2 == a1) {
            if (get_neutral_elem(t1, new_t2)) {
                new_t1 = b1;
                c      = a1;
                first  = true;
                return true;
            }
        }
        else if (is_app_of(t2, t1->get_decl()) && to_app(t2)->get_num_args() == 2) {
            expr * a2 = to_app(t2)->get_arg(0);
            expr * b2 = to_app(t2)->get_arg(1);
            if (b1 == b2) {
                new_t1 = a1;
                new_t2 = a2;
                c      = b2;
                first  = false;
                return true;
            }
            if (a1 == a2) {
                new_t1 = b1;
                new_t2 = b2;
                c      = a1;
                first  = true;
                return true;
            }
            if (t1->get_decl()->is_commutative()) {
                if (a1 == b2) {
                    new_t1 = b1;
                    new_t2 = a2;
                    c      = a1;
                    first  = true; // doesn't really matter for commutative ops.
                    return true;
                }
                if (b1 == a2) {
                    new_t1 = a1;
                    new_t2 = b2;
                    c      = b1;
                    first  = false; // doesn't really matter for commutative ops.
                    return true;
                }
            }
        }
        return false;
    }

    // Return true if t1 and t2 are of the form:
    //   t + a1*x1 + ... + an*xn
    //   t' + a1*x1 + ... + an*xn
    // Store t in new_t1, t' in new_t2 and (a1*x1 + ... + an*xn) in c.
    bool unify_add(app * t1, expr * t2, expr_ref & new_t1, expr_ref & new_t2, expr_ref & c) {
        unsigned num1 = t1->get_num_args();
        expr * const * ms1 = t1->get_args();
        if (num1 < 2)
            return false;
        unsigned num2;
        expr * const * ms2;
        if (m_a_util.is_add(t2)) {
            num2 = to_app(t2)->get_num_args();
            ms2  = to_app(t2)->get_args();
        }
        else {
            num2 = 1;
            ms2  = &t2;
        }
        if (num1 != num2 && num1 != num2 + 1 && num1 != num2 - 1)
            return false;
        new_t1 = 0;
        new_t2 = 0;
        expr_fast_mark1 visited1;
        expr_fast_mark2 visited2;
        for (unsigned i = 0; i < num1; i++) {
            expr * arg = ms1[i];
            visited1.mark(arg);
        }
        for (unsigned i = 0; i < num2; i++) {
            expr * arg = ms2[i];
            visited2.mark(arg);
            if (visited1.is_marked(arg))
                continue;
            if (new_t2)
                return false; // more than one missing term
            new_t2 = arg;
        }
        for (unsigned i = 0; i < num1; i++) {
            expr * arg = ms1[i];
            if (visited2.is_marked(arg))
                continue;
            if (new_t1)
                return false; // more than one missing term
            new_t1 = arg;
        }
        // terms matched...
        bool is_int = m_a_util.is_int(t1);
        if (!new_t1) 
            new_t1 = m_a_util.mk_numeral(rational(0), is_int);
        if (!new_t2)
            new_t2 = m_a_util.mk_numeral(rational(0), is_int);
        // mk common part
        ptr_buffer<expr> args;
        for (unsigned i = 0; i < num1; i++) {
            expr * arg = ms1[i];
            if (arg == new_t1.get())
                continue;
            args.push_back(arg);
        }
        SASSERT(!args.empty());
        if (args.size() == 1) 
            c = args[0];
        else
            c = m_a_util.mk_add(args.size(), args.c_ptr());
        return true;
    }

    bool unify(expr * t1, expr * t2, func_decl * & f, expr_ref & new_t1, expr_ref & new_t2, expr_ref & c, bool & first) {
#if 0
        // Did not work for ring benchmarks

        // Hack for handling more complex cases of + apps
        // such as (+ 2 t1 t2 t3) and (+ 3 t3 t2 t1)
        if (m_a_util.is_add(t1)) {
            first = true; // doesn't matter for AC ops
            f     = to_app(t1)->get_decl();
            if (unify_add(to_app(t1), t2, new_t1, new_t2, c))
                return true;
        }
        if (m_a_util.is_add(t2)) {
            first = true; // doesn't matter for AC ops
            f     = to_app(t2)->get_decl();
            if (unify_add(to_app(t2), t1, new_t2, new_t1, c))
                return true;
        }
#endif

        if (is_arith_bv_app(t1)) {
            f = to_app(t1)->get_decl();
            return unify_core(to_app(t1), t2, new_t1, new_t2, c, first);
        }
        else {
            f = to_app(t2)->get_decl();
            return unify_core(to_app(t2), t1, new_t2, new_t1, c, first);
        }
    }

    // Apply transformations of the form
    //
    // (ite c (+ k1 a) (+ k2 a)) --> (+ (ite c k1 k2) a)   
    // (ite c (* k1 a) (* k2 a)) --> (* (ite c k1 k2) a)
    //
    // These transformations are useful for bit-vector problems, since
    // they will minimize the number of adders/multipliers/etc
    br_status push_ite(func_decl * f, unsigned num, expr * const * args, expr_ref & result) {
        if (!m().is_ite(f))
            return BR_FAILED;
        expr * c = args[0];
        expr * t = args[1];
        expr * e = args[2];
        func_decl * f_prime = 0;
        expr_ref new_t(m()), new_e(m()), common(m());
        bool first;
        TRACE("push_ite", tout << "unifying:\n" << mk_ismt2_pp(t, m()) << "\n" << mk_ismt2_pp(e, m()) << "\n";);
        if (unify(t, e, f_prime, new_t, new_e, common, first)) {
            if (first)
                result = m().mk_app(f_prime, common, m().mk_ite(c, new_t, new_e));
            else 
                result = m().mk_app(f_prime, m().mk_ite(c, new_t, new_e), common);
            return BR_DONE;
        }
        TRACE("push_ite", tout << "failed\n";);
        return BR_FAILED;
    }

    br_status push_ite(expr_ref & result) {
        expr * t = result.get();
        if (m().is_ite(t)) {
            br_status st = push_ite(to_app(t)->get_decl(), to_app(t)->get_num_args(), to_app(t)->get_args(), result);
            if (st != BR_FAILED)
                return st;
        }
        return BR_DONE;
    }

    br_status reduce_app(func_decl * f, unsigned num, expr * const * args, expr_ref & result, proof_ref & result_pr) {
        result_pr = 0;
        br_status st = reduce_app_core(f, num, args, result);
        if (st != BR_DONE && st != BR_FAILED) {
            CTRACE("th_rewriter_step", st != BR_FAILED, 
                   tout << f->get_name() << "\n";
                   for (unsigned i = 0; i < num; i++) tout << mk_ismt2_pp(args[i], m()) << "\n";
                   tout << "---------->\n" << mk_ismt2_pp(result, m()) << "\n";);
            return st;
        }
        if (m_push_ite_bv || m_push_ite_arith) {
            if (st == BR_FAILED)
                st = push_ite(f, num, args, result);
            else
                st = push_ite(result);
        }
        if (m_pull_cheap_ite) {
            if (st == BR_FAILED)
                st = pull_ite(f, num, args, result);
            else
                st = pull_ite(result);
        }
        CTRACE("th_rewriter_step", st != BR_FAILED, 
               tout << f->get_name() << "\n";
               for (unsigned i = 0; i < num; i++) tout << mk_ismt2_pp(args[i], m()) << "\n";
               tout << "---------->\n" << mk_ismt2_pp(result, m()) << "\n";);
        return st;
    }

    bool reduce_quantifier(quantifier * old_q, 
                           expr * new_body, 
                           expr * const * new_patterns, 
                           expr * const * new_no_patterns,
                           expr_ref & result,
                           proof_ref & result_pr) {
        quantifier_ref q1(m());
        proof * p1 = 0;
        if (is_quantifier(new_body) && 
            to_quantifier(new_body)->is_forall() == old_q->is_forall() &&
            !old_q->has_patterns() &&
            !to_quantifier(new_body)->has_patterns()) {
        
            quantifier * nested_q = to_quantifier(new_body);
            
            ptr_buffer<sort> sorts;
            buffer<symbol>   names;   
            sorts.append(old_q->get_num_decls(), old_q->get_decl_sorts());
            names.append(old_q->get_num_decls(), old_q->get_decl_names());
            sorts.append(nested_q->get_num_decls(), nested_q->get_decl_sorts());
            names.append(nested_q->get_num_decls(), nested_q->get_decl_names());
            
            q1 = m().mk_quantifier(old_q->is_forall(),
                                   sorts.size(),
                                   sorts.c_ptr(),
                                   names.c_ptr(),
                                   nested_q->get_expr(),
                                   std::min(old_q->get_weight(), nested_q->get_weight()),
                                   old_q->get_qid(),
                                   old_q->get_skid(),
                                   0, 0, 0, 0);
            
            SASSERT(is_well_sorted(m(), q1));
            
            if (m().proofs_enabled()) {
                SASSERT(old_q->get_expr() == new_body);
                p1 = m().mk_pull_quant(old_q, q1);
            }
        }
        else {
            ptr_buffer<expr> new_patterns_buf;
            ptr_buffer<expr> new_no_patterns_buf;
            
            new_patterns_buf.append(old_q->get_num_patterns(), new_patterns);
            new_no_patterns_buf.append(old_q->get_num_no_patterns(), new_no_patterns);

            remove_duplicates(new_patterns_buf);
            remove_duplicates(new_no_patterns_buf);
            
            q1 = m().update_quantifier(old_q, 
                                       new_patterns_buf.size(), new_patterns_buf.c_ptr(), new_no_patterns_buf.size(), new_no_patterns_buf.c_ptr(),
                                       new_body);
            TRACE("reduce_quantifier", tout << mk_ismt2_pp(old_q, m()) << "\n----->\n" << mk_ismt2_pp(q1, m()) << "\n";);
            SASSERT(is_well_sorted(m(), q1));
        }
    
        elim_unused_vars(m(), q1, result);

        TRACE("reduce_quantifier", tout << "after elim_unused_vars:\n" << mk_ismt2_pp(result, m()) << "\n";);
    
        result_pr = 0;
        if (m().proofs_enabled()) {
            proof * p2 = 0;
            if (q1.get() != result.get())
                p2 = m().mk_elim_unused_vars(q1, result);
            result_pr = m().mk_transitivity(p1, p2);
        }
        return true;
    }

    th_rewriter_cfg(ast_manager & m, params_ref const & p):
        m_b_rw(m, p),
        m_a_rw(m, p),
        m_bv_rw(m, p),
        m_ar_rw(m, p),
        m_dt_rw(m),
        m_f_rw(m, p),
        m_dl_rw(m),
        m_a_util(m),
        m_bv_util(m),
        m_used_dependencies(m),
        m_subst(0) {
        updt_local_params(p);
    }

    void set_substitution(expr_substitution * s) {
        reset();
        m_subst = s;
    }

    void reset() {
        m_subst = 0;
    }

    bool get_subst(expr * s, expr * & t, proof * & pr) {
        if (m_subst == 0)
            return false;
        expr_dependency * d = 0;
        if (m_subst->find(s, t, pr, d)) {
            m_used_dependencies = m().mk_join(m_used_dependencies, d);
            return true;
        }
        return false;
    }

    void set_cancel(bool f) {
        m_a_rw.set_cancel(f);
    }
};

template class rewriter_tpl<th_rewriter_cfg>;

struct th_rewriter::imp : public rewriter_tpl<th_rewriter_cfg> {
    th_rewriter_cfg m_cfg;
    imp(ast_manager & m, params_ref const & p):
        rewriter_tpl<th_rewriter_cfg>(m, m.proofs_enabled(), m_cfg),
        m_cfg(m, p) {
    }
};

th_rewriter::th_rewriter(ast_manager & m, params_ref const & p):
    m_params(p) {
    m_imp = alloc(imp, m, p);
}

ast_manager & th_rewriter::m() const {
    return m_imp->m();
}

void th_rewriter::updt_params(params_ref const & p) {
    m_params = p;
    m_imp->cfg().updt_params(p);
}

void th_rewriter::get_param_descrs(param_descrs & r) {
    bool_rewriter::get_param_descrs(r);
    arith_rewriter::get_param_descrs(r);
    bv_rewriter::get_param_descrs(r);
    array_rewriter::get_param_descrs(r);
    insert_max_memory(r);
    insert_max_steps(r);
    r.insert(":push-ite-arith", CPK_BOOL, "(default: false) push if-then-else over arithmetic terms.");
    r.insert(":push-ite-bv", CPK_BOOL, "(default: false) push if-then-else over bit-vector terms.");
    r.insert(":pull-cheap-ite", CPK_BOOL, "(default: false) pull if-then-else terms when cheap.");
    r.insert(":cache-all", CPK_BOOL, "(default: false) cache all intermediate results.");
}

th_rewriter::~th_rewriter() {
    dealloc(m_imp);
}

unsigned th_rewriter::get_cache_size() const {
    return m_imp->get_cache_size();
}

unsigned th_rewriter::get_num_steps() const {
    return m_imp->get_num_steps();
}

void th_rewriter::set_cancel(bool f) {
    #pragma omp critical (th_rewriter)
    {
        m_imp->set_cancel(f);
        m_imp->cfg().set_cancel(f);
    }
}

void th_rewriter::cleanup() {
    ast_manager & m = m_imp->m();
    #pragma omp critical (th_rewriter)
    {
        dealloc(m_imp);
        m_imp = alloc(imp, m, m_params);
    }
}

void th_rewriter::reset() {
    m_imp->reset();
    m_imp->cfg().reset();
}

void th_rewriter::operator()(expr_ref & term) {
    expr_ref result(term.get_manager());
    m_imp->operator()(term, result);
    term = result;
}

void th_rewriter::operator()(expr * t, expr_ref & result) {
    m_imp->operator()(t, result);
}

void th_rewriter::operator()(expr * t, expr_ref & result, proof_ref & result_pr) {
    m_imp->operator()(t, result, result_pr);
}

void th_rewriter::operator()(expr * n, unsigned num_bindings, expr * const * bindings, expr_ref & result) {
    m_imp->operator()(n, num_bindings, bindings, result);
}

void th_rewriter::set_substitution(expr_substitution * s) {
    m_imp->reset(); // reset the cache
    m_imp->cfg().set_substitution(s);
}

expr_dependency * th_rewriter::get_used_dependencies() {
    return m_imp->cfg().m_used_dependencies;
}

void th_rewriter::reset_used_dependencies() {
    if (get_used_dependencies() != 0) {
        set_substitution(m_imp->cfg().m_subst); // reset cache preserving subst
        m_imp->cfg().m_used_dependencies = 0;
    }
}