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https://github.com/Z3Prover/z3
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guard
Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner
parent
b5676413e4
commit
cd9c752834
2 changed files with 91 additions and 52 deletions
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@ -19,6 +19,7 @@ Revision History:
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#include "util/stats.h"
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#include "ast/ast_util.h"
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#include "ast/for_each_expr.h"
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#include "smt/theory_recfun.h"
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#include "smt/params/smt_params_helper.hpp"
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@ -32,7 +33,7 @@ namespace smt {
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m(m),
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m_plugin(*reinterpret_cast<recfun_decl_plugin*>(m.get_plugin(get_family_id()))),
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m_util(m_plugin.u()),
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m_guard_preds(m),
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m_preds(m),
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m_max_depth(UINT_MAX),
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m_q_case_expand(),
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m_q_body_expand()
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@ -111,7 +112,7 @@ namespace smt {
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void theory_recfun::push_scope_eh() {
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TRACEFN("push_scope");
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theory::push_scope_eh();
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m_guard_preds_lim.push_back(m_guard_preds.size());
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m_preds_lim.push_back(m_preds.size());
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}
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void theory_recfun::pop_scope_eh(unsigned num_scopes) {
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@ -119,14 +120,14 @@ namespace smt {
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theory::pop_scope_eh(num_scopes);
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reset_queues();
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// restore guards
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unsigned new_lim = m_guard_preds_lim.size()-num_scopes;
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unsigned start = m_guard_preds_lim[new_lim];
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for (unsigned i = start; i < m_guard_preds.size(); ++i) {
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m_guards[m_guard_preds.get(i)].pop_back();
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// restore depth book-keeping
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unsigned new_lim = m_preds_lim.size()-num_scopes;
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unsigned start = m_preds_lim[new_lim];
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for (unsigned i = start; i < m_preds.size(); ++i) {
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m_pred_depth.remove(m_preds.get(i));
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}
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m_guard_preds.resize(start);
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m_guard_preds_lim.shrink(new_lim);
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m_preds.resize(start);
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m_preds_lim.shrink(new_lim);
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}
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void theory_recfun::restart_eh() {
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@ -169,24 +170,49 @@ namespace smt {
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m_q_body_expand.clear();
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}
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void theory_recfun::max_depth_limit(ptr_vector<expr> const& guards) {
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/**
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* make clause `depth_limit => ~guard`
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* the guard appears at a depth below the current cutoff.
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*/
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void theory_recfun::assert_max_depth_limit(expr* guard) {
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TRACEFN("max-depth limit");
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literal_vector c;
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// make clause `depth_limit => V_{g : guards of non-recursive cases} g`
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// first literal must be the depth limit one
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app_ref dlimit = m_util.mk_depth_limit_pred(get_max_depth());
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c.push_back(~mk_literal(dlimit));
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enable_trace("recfun");
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TRACE("recfun", ctx().display(tout << c.back() << " " << dlimit << "\n"););
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for (expr * g : guards) {
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c.push_back(mk_literal(g));
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}
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c.push_back(~mk_literal(guard));
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TRACEFN("max-depth limit: add clause " << pp_lits(ctx(), c));
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m_q_clauses.push_back(std::move(c));
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}
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/**
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* retrieve depth associated with predicate or expression.
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*/
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unsigned theory_recfun::get_depth(expr* e) {
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unsigned d = 0;
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m_pred_depth.find(e, d);
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return d;
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}
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/**
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* Update depth of subterms of e with respect to d.
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*/
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void theory_recfun::set_depth(unsigned d, expr* e) {
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struct insert_c {
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theory_recfun& th;
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unsigned m_depth;
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insert_c(theory_recfun& th, unsigned d): th(th), m_depth(d) {}
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void operator()(app* e) {
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if ((th.u().is_defined(e) || th.u().is_case_pred(e)) && !th.m_pred_depth.contains(e)) {
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th.m_pred_depth.insert(e, m_depth);
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}
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}
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void operator()(quantifier*) {}
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void operator()(var*) {}
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};
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insert_c proc(*this, d);
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for_each_expr(proc, e);
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}
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/**
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* if `is_true` and `v = C_f_i(t1...tn)`,
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* then body-expand i-th case of `f(t1...tn)`
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@ -203,6 +229,7 @@ namespace smt {
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// replace `vars` by `args` in `e`
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expr_ref theory_recfun::apply_args(
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unsigned depth,
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recfun::vars const & vars,
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ptr_vector<expr> const & args,
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expr * e) {
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@ -250,7 +277,8 @@ namespace smt {
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SASSERT(e.m_def->is_fun_macro());
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auto & vars = e.m_def->get_vars();
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expr_ref lhs(e.m_lhs, m);
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expr_ref rhs(apply_args(vars, e.m_args, e.m_def->get_macro_rhs()), m);
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unsigned depth = get_depth(e.m_lhs);
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expr_ref rhs(apply_args(depth, vars, e.m_args, e.m_def->get_macro_rhs()), m);
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literal lit = mk_eq_lit(lhs, rhs);
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ctx().mk_th_axiom(get_id(), 1, &lit);
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TRACEFN("macro expansion yields " << mk_pp(rhs, m) << "\n" <<
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@ -273,13 +301,21 @@ namespace smt {
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for (recfun::case_def const & c : e.m_def->get_cases()) {
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// applied predicate to `args`
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app_ref pred_applied = c.apply_case_predicate(e.m_args);
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// cut off cases below max-depth
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unsigned depth = get_depth(pred_applied);
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if (depth >= get_max_depth()) {
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assert_max_depth_limit(pred_applied);
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continue;
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}
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SASSERT(u().owns_app(pred_applied));
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literal concl = mk_literal(pred_applied);
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literal_vector guards;
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guards.push_back(concl);
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for (auto & g : c.get_guards()) {
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expr_ref ga = apply_args(vars, e.m_args, g);
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expr_ref ga = apply_args(depth, vars, e.m_args, g);
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literal guard = mk_literal(ga);
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guards.push_back(~guard);
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literal c[2] = {~concl, guard};
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@ -288,18 +324,8 @@ namespace smt {
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ctx().mk_th_axiom(get_id(), guards);
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if (c.is_immediate()) {
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body_expansion be(c, e.m_args);
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body_expansion be(e.m_lhs, c, e.m_args);
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assert_body_axiom(be);
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// add to set of local assumptions, for depth-limit purpose
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// func_decl* d = pred_applied->get_decl();
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m_guard_preds.push_back(pred_applied);
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auto& vec = m_guards.insert_if_not_there2(e.m_lhs, ptr_vector<expr>())->get_data().m_value;
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vec.push_back(pred_applied);
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if (vec.size() == get_max_depth()) {
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max_depth_limit(vec);
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}
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}
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}
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}
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@ -317,12 +343,13 @@ namespace smt {
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auto & vars = d.get_vars();
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auto & args = e.m_args;
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SASSERT(is_standard_order(vars));
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unsigned depth = get_depth(e.m_lhs);
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expr_ref lhs(u().mk_fun_defined(d, args), m);
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expr_ref rhs = apply_args(vars, args, e.m_cdef->get_rhs());
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expr_ref rhs = apply_args(depth, vars, args, e.m_cdef->get_rhs());
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literal_vector clause;
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for (auto & g : e.m_cdef->get_guards()) {
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expr_ref guard = apply_args(vars, args, g);
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expr_ref guard = apply_args(depth, vars, args, g);
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clause.push_back(~mk_literal(guard));
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if (clause.back() == true_literal) {
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return;
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