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https://github.com/Z3Prover/z3
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5c7eaec566
gc-ing definitions leads to unsoundness when they are not replayed. Instead of attempting to replay definitions theory internalization is irredundant by default. This is also the old solver behavior where TH_LEMMA is essentially never used, but is valid for top-level theory lemmas.
227 lines
6.5 KiB
C++
227 lines
6.5 KiB
C++
/*++
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Copyright (c) 2020 Microsoft Corporation
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Module Name:
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euf_ackerman.cpp
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Abstract:
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Ackerman reduction plugin for EUF
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Author:
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Nikolaj Bjorner (nbjorner) 2020-08-28
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--*/
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#include "sat/smt/euf_solver.h"
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#include "sat/smt/euf_ackerman.h"
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namespace euf {
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ackerman::ackerman(solver& ctx, ast_manager& m): ctx(ctx), m(m) {
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new_tmp();
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}
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ackerman::~ackerman() {
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reset();
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dealloc(m_tmp_inference);
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}
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void ackerman::reset() {
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for (inference* inf : m_table) {
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m.dec_ref(inf->a);
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m.dec_ref(inf->b);
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m.dec_ref(inf->c);
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dealloc(inf);
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}
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m_table.reset();
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m_queue = nullptr;
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}
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void ackerman::insert(expr* a, expr* b, expr* lca) {
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if (a->get_id() > b->get_id())
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std::swap(a, b);
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inference& inf = *m_tmp_inference;
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inf.a = a;
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inf.b = b;
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inf.c = lca;
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inf.is_cc = false;
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inf.m_count = 0;
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insert();
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}
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void ackerman::insert(app* a, app* b) {
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if (a->get_id() > b->get_id())
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std::swap(a, b);
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inference& inf = *m_tmp_inference;
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inf.a = a;
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inf.b = b;
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inf.c = nullptr;
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inf.is_cc = true;
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inf.m_count = 0;
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insert();
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}
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void ackerman::insert() {
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inference* inf = m_tmp_inference;
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inference* other = m_table.insert_if_not_there(inf);
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if (other == inf) {
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m.inc_ref(inf->a);
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m.inc_ref(inf->b);
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m.inc_ref(inf->c);
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new_tmp();
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}
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other->m_count++;
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inference::push_to_front(m_queue, other);
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}
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void ackerman::remove(inference* inf) {
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inference::remove_from(m_queue, inf);
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m_table.erase(inf);
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m.dec_ref(inf->a);
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m.dec_ref(inf->b);
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m.dec_ref(inf->c);
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dealloc(inf);
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}
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void ackerman::new_tmp() {
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m_tmp_inference = alloc(inference);
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m_tmp_inference->init(m_tmp_inference);
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}
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bool ackerman::enable_cc(app* a, app* b) {
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if (!ctx.enable_ackerman_axioms(a))
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return false;
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if (!ctx.enable_ackerman_axioms(b))
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return false;
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for (expr* arg : *a)
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if (!ctx.enable_ackerman_axioms(arg))
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return false;
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for (expr* arg : *b)
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if (!ctx.enable_ackerman_axioms(arg))
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return false;
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return true;
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}
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bool ackerman::enable_eq(expr* a, expr* b, expr* c) {
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return ctx.enable_ackerman_axioms(a) &&
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ctx.enable_ackerman_axioms(b) &&
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ctx.enable_ackerman_axioms(c);
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}
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void ackerman::cg_conflict_eh(expr * n1, expr * n2) {
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if (!is_app(n1) || !is_app(n2))
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return;
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if (!ctx.enable_ackerman_axioms(n1))
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return;
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SASSERT(!ctx.m_drating);
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app* a = to_app(n1);
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app* b = to_app(n2);
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if (a->get_decl() != b->get_decl() || a->get_num_args() != b->get_num_args())
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return;
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if (!enable_cc(a, b))
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return;
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TRACE("ack", tout << "conflict eh: " << mk_pp(a, m) << " == " << mk_pp(b, m) << "\n";);
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insert(a, b);
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gc();
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}
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void ackerman::used_eq_eh(expr* a, expr* b, expr* c) {
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if (a == b || a == c || b == c)
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return;
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if (ctx.m_drating)
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return;
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if (!enable_eq(a, b, c))
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return;
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TRACE("ack", tout << mk_pp(a, m) << " " << mk_pp(b, m) << " " << mk_pp(c, m) << "\n";);
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insert(a, b, c);
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gc();
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}
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void ackerman::used_cc_eh(app* a, app* b) {
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if (ctx.m_drating)
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return;
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TRACE("ack", tout << "used cc: " << mk_pp(a, m) << " == " << mk_pp(b, m) << "\n";);
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SASSERT(a->get_decl() == b->get_decl());
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SASSERT(a->get_num_args() == b->get_num_args());
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if (!enable_cc(a, b))
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return;
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insert(a, b);
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gc();
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}
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void ackerman::gc() {
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m_num_propagations_since_last_gc++;
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if (m_num_propagations_since_last_gc <= ctx.m_config.m_dack_gc)
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return;
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m_num_propagations_since_last_gc = 0;
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while (m_table.size() > m_gc_threshold)
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remove(m_queue->prev());
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m_gc_threshold *= 110;
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m_gc_threshold /= 100;
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m_gc_threshold++;
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}
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void ackerman::propagate() {
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SASSERT(ctx.s().at_base_lvl());
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auto* n = m_queue;
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inference* k = nullptr;
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unsigned num_prop = static_cast<unsigned>(ctx.s().get_stats().m_conflict * ctx.m_config.m_dack_factor);
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num_prop = std::min(num_prop, m_table.size());
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for (unsigned i = 0; i < num_prop; ++i, n = k) {
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k = n->next();
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if (n->m_count < ctx.m_config.m_dack_threshold)
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continue;
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if (n->m_count >= m_high_watermark && num_prop < m_table.size())
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++num_prop;
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if (n->is_cc)
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add_cc(n->a, n->b);
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else
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add_eq(n->a, n->b, n->c);
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++ctx.m_stats.m_ackerman;
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remove(n);
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}
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}
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void ackerman::add_cc(expr* _a, expr* _b) {
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app* a = to_app(_a);
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app* b = to_app(_b);
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TRACE("ack", tout << mk_pp(a, m) << " " << mk_pp(b, m) << "\n";);
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sat::literal_vector lits;
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unsigned sz = a->get_num_args();
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for (unsigned i = 0; i < sz; ++i) {
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expr* ai = a->get_arg(i);
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expr* bi = b->get_arg(i);
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if (ai != bi) {
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expr_ref eq = ctx.mk_eq(ai, bi);
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lits.push_back(~ctx.mk_literal(eq));
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}
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}
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expr_ref eq = ctx.mk_eq(a, b);
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lits.push_back(ctx.mk_literal(eq));
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th_proof_hint* ph = ctx.mk_cc_proof_hint(lits, a, b);
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ctx.s().mk_clause(lits, sat::status::th(true, m.get_basic_family_id(), ph));
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}
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void ackerman::add_eq(expr* a, expr* b, expr* c) {
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if (a == c || b == c)
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return;
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sat::literal lits[3];
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expr_ref eq1(ctx.mk_eq(a, c), m);
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expr_ref eq2(ctx.mk_eq(b, c), m);
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expr_ref eq3(ctx.mk_eq(a, b), m);
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TRACE("ack", tout << mk_pp(a, m) << " " << mk_pp(b, m) << " " << mk_pp(c, m) << "\n";);
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lits[0] = ~ctx.mk_literal(eq1);
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lits[1] = ~ctx.mk_literal(eq2);
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lits[2] = ctx.mk_literal(eq3);
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th_proof_hint* ph = ctx.mk_tc_proof_hint(lits);
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ctx.s().add_clause(3, lits, sat::status::th(true, m.get_basic_family_id(), ph));
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}
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}
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