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guard

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2018-10-21 20:46:12 -07:00
parent b5676413e4
commit cd9c752834
2 changed files with 91 additions and 52 deletions
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95
src/smt/theory_recfun.cpp
View file

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

48
src/smt/theory_recfun.h
View file

@ -35,11 +35,11 @@ namespace smt {
// one case-expansion of `f(t1...tn)`
struct case_expansion {
expr * m_lhs; // the term to expand
app * m_lhs; // the term to expand
recfun_def * m_def;
ptr_vector<expr> m_args;
case_expansion(recfun_util& u, app * n) : m_lhs(n), m_def(0), m_args()
{
case_expansion(recfun_util& u, app * n) :
m_lhs(n), m_def(nullptr), m_args() {
SASSERT(u.is_defined(n));
func_decl * d = n->get_decl();
const symbol& name = d->get_name();
@ -66,16 +66,20 @@ namespace smt {
// one body-expansion of `f(t1...tn)` using a `C_f_i(t1...tn)`
struct body_expansion {
app* m_lhs;
recfun_case_def const * m_cdef;
ptr_vector<expr> m_args;
body_expansion(recfun_util& u, app * n) : m_cdef(0), m_args() {
body_expansion(recfun_util& u, app * n) : m_lhs(n), m_cdef(0), m_args() {
m_cdef = &u.get_case_def(n);
m_args.append(n->get_num_args(), n->get_args());
}
body_expansion(recfun_case_def const & d, ptr_vector<expr> & args) : m_cdef(&d), m_args(args) {}
body_expansion(body_expansion const & from): m_cdef(from.m_cdef), m_args(from.m_args) {}
body_expansion(body_expansion && from) : m_cdef(from.m_cdef), m_args(std::move(from.m_args)) {}
body_expansion(app* lhs, recfun_case_def const & d, ptr_vector<expr> & args) :
m_lhs(lhs), m_cdef(&d), m_args(args) {}
body_expansion(body_expansion const & from):
m_lhs(from.m_lhs), m_cdef(from.m_cdef), m_args(from.m_args) {}
body_expansion(body_expansion && from) :
m_lhs(from.m_lhs), m_cdef(from.m_cdef), m_args(std::move(from.m_args)) {}
};
struct pp_body_expansion {
@ -86,14 +90,16 @@ namespace smt {
friend std::ostream& operator<<(std::ostream&, pp_body_expansion const &);
ast_manager& m;
recfun_decl_plugin& m_plugin;
recfun_util& m_util;
stats m_stats;
obj_map<expr, ptr_vector<expr> > m_guards;
app_ref_vector m_guard_preds;
unsigned_vector m_guard_preds_lim;
unsigned m_max_depth; // for fairness and termination
ast_manager& m;
recfun_decl_plugin& m_plugin;
recfun_util& m_util;
stats m_stats;
// book-keeping for depth of predicates
obj_map<expr, unsigned> m_pred_depth;
expr_ref_vector m_preds;
unsigned_vector m_preds_lim;
unsigned m_max_depth; // for fairness and termination
vector<case_expansion> m_q_case_expand;
vector<body_expansion> m_q_body_expand;
@ -107,14 +113,20 @@ namespace smt {
bool is_case_pred(enode * e) const { return is_case_pred(e->get_owner()); }
void reset_queues();
expr_ref apply_args(recfun::vars const & vars, ptr_vector<expr> const & args, expr * e); //!< substitute variables by args
expr_ref apply_args(unsigned depth, recfun::vars const & vars, ptr_vector<expr> const & args, expr * e); //!< substitute variables by args
void assert_macro_axiom(case_expansion & e);
void assert_case_axioms(case_expansion & e);
void assert_body_axiom(body_expansion & e);
literal mk_literal(expr* e);
void max_depth_limit(ptr_vector<expr> const& guards);
void assert_max_depth_limit(expr* guard);
unsigned get_depth(expr* e);
void set_depth(unsigned d, expr* e);
literal mk_eq_lit(expr* l, expr* r);
bool is_standard_order(recfun::vars const& vars) const { return vars.size() == 0 || vars[vars.size()-1]->get_idx() == 0; }
bool is_standard_order(recfun::vars const& vars) const {
return vars.size() == 0 || vars[vars.size()-1]->get_idx() == 0;
}
protected:
void push_case_expand(case_expansion&& e) { m_q_case_expand.push_back(e); }
void push_body_expand(body_expansion&& e) { m_q_body_expand.push_back(e); }