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expand deep stores by lambdas to avoid expanding select/store axioms

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-11-03 10:28:58 +01:00
parent d866a93627
commit a78f899225
5 changed files with 116 additions and 36 deletions
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61
src/ast/rewriter/array_rewriter.cpp
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@ -28,6 +28,7 @@ void array_rewriter::updt_params(params_ref const & _p) {
m_sort_store = p.sort_store();
m_expand_select_store = p.expand_select_store();
m_expand_store_eq = p.expand_store_eq();
m_expand_nested_stores = p.expand_nested_stores();
m_expand_select_ite = false;
}
@ -630,6 +631,49 @@ bool array_rewriter::add_store(expr_ref_vector& args, unsigned num_idxs, expr* e
return true;
}
bool array_rewriter::is_expandable_store(expr* s) {
unsigned count = s->get_ref_count();
unsigned depth = 0;
while (m_util.is_store(s)) {
s = to_app(s)->get_arg(0);
count += s->get_ref_count();
depth++;
}
return (depth >= 3 && count <= depth*2);
}
expr_ref array_rewriter::expand_store(expr* s) {
ptr_vector<app> stores;
expr_ref result(m());
while (m_util.is_store(s)) {
stores.push_back(to_app(s));
s = to_app(s)->get_arg(0);
}
stores.reverse();
expr_ref_vector args(m()), eqs(m());
ptr_vector<sort> sorts;
svector<symbol> names;
sort* srt = m().get_sort(s);
args.push_back(s);
for (unsigned i = get_array_arity(srt); i-- > 0; ) {
args.push_back(m().mk_var(i, get_array_domain(srt, i)));
sorts.push_back(get_array_domain(srt, i));
names.push_back(symbol(i));
}
names.reverse();
sorts.reverse();
result = m_util.mk_select(args);
for (app* st : stores) {
eqs.reset();
for (unsigned i = 1; i < args.size(); ++i) {
eqs.push_back(m().mk_eq(args.get(i), st->get_arg(i)));
}
result = m().mk_ite(mk_and(eqs), st->get_arg(args.size()), result);
}
result = m().mk_lambda(sorts.size(), sorts.c_ptr(), names.c_ptr(), result);
return result;
}
br_status array_rewriter::mk_eq_core(expr * lhs, expr * rhs, expr_ref & result) {
TRACE("array_rewriter", tout << mk_pp(lhs, m()) << " " << mk_pp(rhs, m()) << "\n";);
expr* v = nullptr;
@ -642,6 +686,22 @@ br_status array_rewriter::mk_eq_core(expr * lhs, expr * rhs, expr_ref & result)
result = m().update_quantifier(lam, quantifier_kind::forall_k, e);
return BR_REWRITE2;
}
expr_ref lh1(m()), rh1(m());
if (m_expand_nested_stores) {
if (is_expandable_store(lhs)) {
lh1 = expand_store(lhs);
}
if (is_expandable_store(rhs)) {
rh1 = expand_store(rhs);
}
if (lh1 || rh1) {
if (!lh1) lh1 = lhs;
if (!rh1) rh1 = rhs;
result = m().mk_eq(lh1, rh1);
return BR_REWRITE_FULL;
}
}
if (!m_expand_store_eq) {
return BR_FAILED;
}
@ -666,6 +726,7 @@ br_status array_rewriter::mk_eq_core(expr * lhs, expr * rhs, expr_ref & result)
}
}
#endif
expr* lhs1 = lhs;
while (m_util.is_store(lhs1)) {
lhs1 = to_app(lhs1)->get_arg(0);