mirror of
https://github.com/Z3Prover/z3
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294 lines
9.3 KiB
C++
294 lines
9.3 KiB
C++
/*++
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Copyright (c) 2020 Microsoft Corporation
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Module Name:
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q_eval.cpp
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Abstract:
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Evaluation of clauses
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Author:
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Nikolaj Bjorner (nbjorner) 2021-01-24
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--*/
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#pragma once
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#include "sat/smt/q_eval.h"
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#include "sat/smt/euf_solver.h"
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#include "sat/smt/q_solver.h"
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namespace q {
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struct eval::scoped_mark_reset {
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eval& e;
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scoped_mark_reset(eval& e): e(e) {}
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~scoped_mark_reset() { e.m_mark.reset(); }
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};
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eval::eval(euf::solver& ctx):
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ctx(ctx),
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m(ctx.get_manager())
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{}
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lbool eval::operator()(euf::enode* const* binding, clause& c, unsigned& idx) {
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scoped_mark_reset _sr(*this);
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idx = UINT_MAX;
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unsigned sz = c.m_lits.size();
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unsigned n = c.num_decls();
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m_indirect_nodes.reset();
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for (unsigned i = 0; i < sz; ++i) {
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unsigned lim = m_indirect_nodes.size();
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lit l = c[i];
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lbool cmp = compare(n, binding, l.lhs, l.rhs);
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switch (cmp) {
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case l_false:
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m_indirect_nodes.shrink(lim);
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if (!l.sign)
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break;
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if (i > 0)
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std::swap(c[0], c[i]);
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return l_true;
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case l_true:
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m_indirect_nodes.shrink(lim);
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if (l.sign)
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break;
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if (i > 0)
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std::swap(c[0], c[i]);
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return l_true;
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case l_undef:
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TRACE("q", tout << l.lhs << " ~~ " << l.rhs << " is undef\n";);
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if (idx == 0) {
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idx = UINT_MAX;
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return l_undef;
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}
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if (i > 0)
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std::swap(c[0], c[i]);
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idx = 0;
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break;
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}
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}
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if (idx == UINT_MAX)
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return l_false;
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return l_undef;
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}
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lbool eval::operator()(euf::enode* const* binding, clause& c) {
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unsigned idx = 0;
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return (*this)(binding, c, idx);
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}
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lbool eval::compare(unsigned n, euf::enode* const* binding, expr* s, expr* t) {
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if (s == t)
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return l_true;
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if (m.are_distinct(s, t))
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return l_false;
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euf::enode* sn = (*this)(n, binding, s);
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euf::enode* tn = (*this)(n, binding, t);
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if (sn) sn = sn->get_root();
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if (tn) tn = tn->get_root();
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TRACE("q", tout << mk_pp(s, m) << " ~~ " << mk_pp(t, m) << "\n";
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tout << ctx.bpp(sn) << " " << ctx.bpp(tn) << "\n";);
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lbool c;
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if (sn && sn == tn)
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return l_true;
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if (sn && tn && ctx.get_egraph().are_diseq(sn, tn))
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return l_false;
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if (sn && tn)
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return l_undef;
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if (!sn && !tn)
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return compare_rec(n, binding, s, t);
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if (!tn && sn) {
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std::swap(tn, sn);
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std::swap(t, s);
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}
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for (euf::enode* t1 : euf::enode_class(tn))
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if (c = compare_rec(n, binding, s, t1->get_expr()), c != l_undef)
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return c;
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return l_undef;
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}
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// f(p1) = f(p2) if p1 = p2
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// f(p1) != f(p2) if p1 != p2 and f is injective
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lbool eval::compare_rec(unsigned n, euf::enode* const* binding, expr* s, expr* t) {
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if (m.are_equal(s, t))
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return l_true;
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if (m.are_distinct(s, t))
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return l_false;
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if (!is_app(s) || !is_app(t))
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return l_undef;
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if (to_app(s)->get_decl() != to_app(t)->get_decl())
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return l_undef;
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if (to_app(s)->get_num_args() != to_app(t)->get_num_args())
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return l_undef;
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bool is_injective = to_app(s)->get_decl()->is_injective();
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bool has_undef = false;
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for (unsigned i = to_app(s)->get_num_args(); i-- > 0; ) {
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switch (compare(n, binding, to_app(s)->get_arg(i), to_app(t)->get_arg(i))) {
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case l_true:
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break;
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case l_false:
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if (is_injective)
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return l_false;
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return l_undef;
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case l_undef:
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if (!is_injective)
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return l_undef;
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has_undef = true;
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break;
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}
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}
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return has_undef ? l_undef : l_true;
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}
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euf::enode* eval::operator()(unsigned n, euf::enode* const* binding, expr* e) {
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if (is_ground(e))
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return ctx.get_egraph().find(e);
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if (m_mark.is_marked(e))
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return m_eval[e->get_id()];
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ptr_buffer<expr> todo;
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ptr_buffer<euf::enode> args;
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todo.push_back(e);
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while (!todo.empty()) {
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expr* t = todo.back();
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SASSERT(!is_ground(t) || ctx.get_egraph().find(t));
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if (is_ground(t)) {
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m_eval.setx(t->get_id(), ctx.get_egraph().find(t), nullptr);
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SASSERT(m_eval[t->get_id()]);
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todo.pop_back();
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continue;
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}
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if (m_mark.is_marked(t)) {
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todo.pop_back();
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continue;
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}
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if (is_var(t)) {
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m_mark.mark(t);
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m_eval.setx(t->get_id(), binding[n - 1 - to_var(t)->get_idx()], nullptr);
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todo.pop_back();
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continue;
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}
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if (!is_app(t))
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return nullptr;
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args.reset();
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for (expr* arg : *to_app(t)) {
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if (m_mark.is_marked(arg))
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args.push_back(m_eval[arg->get_id()]);
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else
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todo.push_back(arg);
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}
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if (args.size() == to_app(t)->get_num_args()) {
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euf::enode* n = ctx.get_egraph().find(t, args.size(), args.c_ptr());
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if (!n)
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return nullptr;
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m_indirect_nodes.push_back(n);
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m_eval.setx(t->get_id(), n, nullptr);
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m_mark.mark(t);
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todo.pop_back();
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}
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}
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return m_eval[e->get_id()];
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}
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void eval::explain(clause& c, unsigned literal_idx, euf::enode* const* b) {
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unsigned n = c.num_decls();
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for (unsigned i = c.size(); i-- > 0; ) {
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if (i == literal_idx)
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continue;
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auto const& lit = c[i];
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if (lit.sign)
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explain_eq(n, b, lit.lhs, lit.rhs);
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else
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explain_diseq(n, b, lit.lhs, lit.rhs);
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}
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}
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void eval::explain_eq(unsigned n, euf::enode* const* binding, expr* s, expr* t) {
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SASSERT(l_true == compare(n, binding, s, t));
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if (s == t)
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return;
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euf::enode* sn = (*this)(n, binding, s);
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euf::enode* tn = (*this)(n, binding, t);
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if (sn && tn) {
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SASSERT(sn->get_root() == tn->get_root());
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ctx.add_antecedent(sn, tn);
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return;
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}
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if (!sn && tn) {
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std::swap(sn, tn);
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std::swap(s, t);
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}
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if (sn && !tn) {
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for (euf::enode* s1 : euf::enode_class(sn)) {
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if (l_true == compare_rec(n, binding, t, s1->get_expr())) {
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ctx.add_antecedent(sn, s1);
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explain_eq(n, binding, t, s1->get_expr());
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return;
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}
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}
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UNREACHABLE();
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}
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SASSERT(is_app(s) && is_app(t));
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SASSERT(to_app(s)->get_decl() == to_app(t)->get_decl());
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for (unsigned i = to_app(s)->get_num_args(); i-- > 0; )
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explain_eq(n, binding, to_app(s)->get_arg(i), to_app(t)->get_arg(i));
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}
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void eval::explain_diseq(unsigned n, euf::enode* const* binding, expr* s, expr* t) {
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SASSERT(l_false == compare(n, binding, s, t));
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if (m.are_distinct(s, t))
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return;
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euf::enode* sn = (*this)(n, binding, s);
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euf::enode* tn = (*this)(n, binding, t);
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if (sn && tn && ctx.get_egraph().are_diseq(sn, tn)) {
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ctx.add_diseq_antecedent(sn, tn);
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return;
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}
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if (!sn && tn) {
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std::swap(sn, tn);
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std::swap(s, t);
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}
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if (sn && !tn) {
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for (euf::enode* s1 : euf::enode_class(sn)) {
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if (l_false == compare_rec(n, binding, t, s1->get_expr())) {
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ctx.add_antecedent(sn, s1);
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explain_diseq(n, binding, t, s1->get_expr());
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return;
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}
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}
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UNREACHABLE();
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}
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SASSERT(is_app(s) && is_app(t));
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app* at = to_app(t);
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app* as = to_app(s);
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SASSERT(as->get_decl() == at->get_decl());
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for (unsigned i = as->get_num_args(); i-- > 0; ) {
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if (l_false == compare_rec(n, binding, as->get_arg(i), at->get_arg(i))) {
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explain_eq(n, binding, as->get_arg(i), at->get_arg(i));
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return;
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}
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}
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UNREACHABLE();
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}
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void eval::explain(sat::literal l, justification& j, sat::literal_vector& r, bool probing) {
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unsigned l_idx = 0;
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clause& c = j.m_clause;
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for (; l_idx < c.size(); ++l_idx) {
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if (c[l_idx].lhs == j.m_lhs && c[l_idx].rhs == j.m_rhs && c[l_idx].sign == j.m_sign)
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break;
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}
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explain(c, l_idx, j.m_binding);
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r.push_back(c.m_literal);
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(void)probing; // ignored
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}
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}
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