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#5482 fix default case for model construction

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port mg_merge functionality from theory_array_base that ensures default values in arrays congruent modulo stores are the same
This commit is contained in:
Nikolaj Bjorner 2021-08-29 17:30:39 -07:00
parent 9b5ec6d004
commit 148cb83b0d
4 changed files with 141 additions and 1 deletions
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125
src/sat/smt/array_model.cpp
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@ -20,7 +20,11 @@ Author:
#include "sat/smt/euf_solver.h"
namespace array {
void solver::init_model() {
collect_defaults();
}
bool solver::add_dep(euf::enode* n, top_sort<euf::enode>& dep) {
if (!a.is_array(n->get_expr())) {
@ -41,6 +45,10 @@ namespace array {
for (euf::enode* k : euf::enode_class(n))
if (a.is_const(k->get_expr()))
dep.add(n, k->get_arg(0));
theory_var v = get_th_var(n);
euf::enode* d = get_default(v);
if (d)
dep.add(n, d);
if (!dep.deps().contains(n))
dep.insert(n, nullptr);
return true;
@ -57,6 +65,17 @@ namespace array {
func_interp * fi = alloc(func_interp, m, arity);
mdl.register_decl(f, fi);
theory_var v = get_th_var(n);
euf::enode* d = get_default(v);
if (d && !fi->get_else())
fi->set_else(values.get(d->get_root_id()));
if (!fi->get_else() && get_else(v))
fi->set_else(get_else(v));
#if 0
// this functionality is already taken care of by model_init.
if (!fi->get_else())
for (euf::enode* k : euf::enode_class(n))
if (a.is_const(k->get_expr()))
@ -66,6 +85,7 @@ namespace array {
for (euf::enode* p : euf::enode_parents(n))
if (a.is_default(p->get_expr()))
fi->set_else(values.get(p->get_root_id()));
#endif
if (!fi->get_else()) {
expr* else_value = nullptr;
@ -90,6 +110,9 @@ namespace array {
fi->set_else(else_value);
}
if (!get_else(v) && fi->get_else())
set_else(v, fi->get_else());
for (euf::enode* p : euf::enode_parents(n)) {
if (a.is_select(p->get_expr()) && p->get_arg(0)->get_root() == n) {
expr* value = values.get(p->get_root_id(), nullptr);
@ -175,4 +198,104 @@ namespace array {
return table_diff(r1, r2, else1) || table_diff(r2, r1, else2);
}
void solver::collect_defaults() {
unsigned num_vars = get_num_vars();
m_defaults.reset();
m_else_values.reset();
m_parents.reset();
m_parents.resize(num_vars, -1);
m_defaults.resize(num_vars);
m_else_values.resize(num_vars);
//
// Create equivalence classes for defaults.
//
for (unsigned v = 0; v < num_vars; ++v) {
euf::enode * n = var2enode(v);
expr* e = n->get_expr();
theory_var r = get_representative(v);
mg_merge(v, r);
if (a.is_const(e))
set_default(v, n->get_arg(0));
else if (a.is_store(e)) {
theory_var w = get_th_var(n->get_arg(0));
SASSERT(w != euf::null_theory_var);
mg_merge(v, get_representative(w));
TRACE("array", tout << "merge: " << ctx.bpp(n) << " " << v << " " << w << "\n";);
}
else if (a.is_default(e)) {
theory_var w = get_th_var(n->get_arg(0));
SASSERT(w != euf::null_theory_var);
set_default(w, n);
}
}
}
void solver::set_default(theory_var v, euf::enode* n) {
TRACE("array", tout << "set default: " << v << " " << ctx.bpp(n) << "\n";);
v = mg_find(v);
if (!m_defaults[v])
m_defaults[v] = n;
}
euf::enode* solver::get_default(theory_var v) {
return m_defaults[mg_find(v)];
}
void solver::set_else(theory_var v, expr* e) {
m_else_values[mg_find(v)] = e;
}
expr* solver::get_else(theory_var v) {
return m_else_values[mg_find(v)];
}
euf::theory_var solver::mg_find(theory_var n) {
if (m_parents[n] < 0)
return n;
theory_var n0 = n;
n = m_parents[n0];
if (m_parents[n] < -1)
return n;
while (m_parents[n] >= 0)
n = m_parents[n];
// compress path.
while (m_parents[n0] >= 0) {
theory_var n1 = m_parents[n0];
m_parents[n0] = n;
n0 = n1;
}
return n;
}
void solver::mg_merge(theory_var u, theory_var v) {
u = mg_find(u);
v = mg_find(v);
if (u != v) {
SASSERT(m_parents[u] < 0);
SASSERT(m_parents[v] < 0);
if (m_parents[u] > m_parents[v])
std::swap(u, v);
m_parents[u] += m_parents[v];
m_parents[v] = u;
if (!m_defaults[u])
m_defaults[u] = m_defaults[v];
CTRACE("array", m_defaults[v],
tout << ctx.bpp(m_defaults[v]->get_root()) << "\n";
tout << ctx.bpp(m_defaults[u]->get_root()) << "\n";
);
// NB. it may be the case that m_defaults[u] != m_defaults[v]
// when m and n are finite arrays.
}
}
}