mirror of
https://github.com/Z3Prover/z3
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b6f8538d20
p != 0 ==> odd(r)
... added premise p != 0
parity(p) < k ==> r <= 2^(N - k) - 1
... do this also in the other branch
(otherwise we hit the UNREACHABLE in bench3)
115 lines
3.9 KiB
C++
115 lines
3.9 KiB
C++
/*++
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Copyright (c) 2021 Microsoft Corporation
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Module Name:
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Op constraint.
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lshr: r == p >> q
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ashr: r == p >>a q
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lshl: r == p << q
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and: r == p & q
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not: r == ~p
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Author:
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Jakob Rath, Nikolaj Bjorner (nbjorner) 2021-12-09
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--*/
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#pragma once
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#include "math/polysat/constraint.h"
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#include <optional>
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namespace polysat {
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class solver;
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class op_constraint final : public constraint {
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public:
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enum class code {
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/// r is the logical right shift of p by q
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lshr_op,
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/// r is the arithmetic right shift of p by q
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ashr_op,
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/// r is the left shift of p by q
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shl_op,
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/// r is the bit-wise 'and' of p and q
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and_op,
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/// r is the smallest multiplicative pseudo-inverse of p;
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/// by definition we set r == 0 when p == 0.
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/// Note that in general, there are 2^parity(p) many pseudo-inverses of p.
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inv_op
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};
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protected:
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friend class constraint_manager;
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code m_op;
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pdd m_p; // operand1
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pdd m_q; // operand2
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pdd m_r; // result
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op_constraint(code c, pdd const& p, pdd const& q, pdd const& r);
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lbool eval(pdd const& p, pdd const& q, pdd const& r) const;
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clause_ref produce_lemma(solver& s, assignment const& a);
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clause_ref lemma_lshr(solver& s, assignment const& a);
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static lbool eval_lshr(pdd const& p, pdd const& q, pdd const& r);
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bool propagate_bits_lshr(solver& s, bool is_positive);
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clause_ref lemma_shl(solver& s, assignment const& a);
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static lbool eval_shl(pdd const& p, pdd const& q, pdd const& r);
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bool propagate_bits_shl(solver& s, bool is_positive);
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clause_ref lemma_and(solver& s, assignment const& a);
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static lbool eval_and(pdd const& p, pdd const& q, pdd const& r);
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bool propagate_bits_and(solver& s, bool is_positive);
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clause_ref lemma_inv(solver& s, assignment const& a);
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static lbool eval_inv(pdd const& p, pdd const& r);
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std::ostream& display(std::ostream& out, char const* eq) const;
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void activate(solver& s);
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void activate_and(solver& s);
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public:
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~op_constraint() override {}
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pdd const& p() const { return m_p; }
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pdd const& q() const { return m_q; }
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pdd const& r() const { return m_r; }
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std::ostream& display(std::ostream& out, lbool status) const override;
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std::ostream& display(std::ostream& out) const override;
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lbool eval() const override;
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lbool eval(assignment const& a) const override;
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void narrow(solver& s, bool is_positive, bool first) override;
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bool propagate_bits(solver& s, bool is_positive) override;
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virtual clause_ref produce_lemma(solver& s, assignment const& a, bool is_positive) override;
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unsigned hash() const override;
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bool operator==(constraint const& other) const override;
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bool is_eq() const override { return false; }
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void add_to_univariate_solver(pvar v, solver& s, univariate_solver& us, unsigned dep, bool is_positive) const override;
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};
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struct op_constraint_args {
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op_constraint::code op;
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// NOTE: this is only optional because table2map requires a default constructor
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std::optional<std::pair<pdd, pdd>> args;
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op_constraint_args() = default;
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op_constraint_args(op_constraint::code op, pdd lhs, pdd rhs)
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: op(op), args({std::move(lhs), std::move(rhs)}) {}
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bool operator==(op_constraint_args const& other) const {
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return op == other.op && args == other.args;
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}
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unsigned hash() const {
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unsigned const lhs_hash = args ? args->first.hash() : 0;
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unsigned const rhs_hash = args ? args->second.hash() : 0;
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return mk_mix(static_cast<unsigned>(op), lhs_hash, rhs_hash);
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}
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};
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}
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