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stubs for stronger array equality rewriting

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2019-03-03 14:11:05 -08:00
parent 6c331279ae
commit 7b4c919fcf
4 changed files with 110 additions and 19 deletions
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17
src/ast/array_decl_plugin.cpp
View file

@ -580,6 +580,23 @@ bool array_recognizers::is_const(expr* e, expr*& v) const {
return is_const(e) && (v = to_app(e)->get_arg(0), true);
}
bool array_recognizers::is_store_ext(expr* _e, expr_ref& a, expr_ref_vector& args, expr_ref& value) {
ast_manager& m = a.m();
if (is_store(_e)) {
app* e = to_app(_e);
a = e->get_arg(0);
unsigned sz = e->get_num_args();
args.reset();
for (unsigned i = 1; i < sz-1; ++i) {
args.push_back(e->get_arg(i));
}
value = e->get_arg(sz-1);
return true;
}
return false;
}
array_util::array_util(ast_manager& m):
array_recognizers(m.mk_family_id("array")),
m_manager(m) {

2
src/ast/array_decl_plugin.h
View file

@ -154,6 +154,8 @@ public:
func_decl * get_as_array_func_decl(func_decl* f) const;
bool is_const(expr* e, expr*& v) const;
bool is_store_ext(expr* e, expr_ref& a, expr_ref_vector& args, expr_ref& value);
};
class array_util : public array_recognizers {

108
src/ast/rewriter/array_rewriter.cpp
View file

@ -389,10 +389,96 @@ br_status array_rewriter::mk_set_subset(expr * arg1, expr * arg2, expr_ref & res
return BR_REWRITE3;
}
void array_rewriter::mk_eq(expr* e, expr* lhs, expr* rhs, expr_ref_vector& fmls) {
expr_ref tmp1(m()), tmp2(m());
expr_ref a(m()), v(m());
expr_ref_vector args0(m()), args(m());
while (m_util.is_store_ext(e, a, args0, v)) {
args.reset();
args.push_back(lhs);
args.append(args0);
mk_select(args.size(), args.c_ptr(), tmp1);
args[0] = rhs;
mk_select(args.size(), args.c_ptr(), tmp2);
fmls.push_back(m().mk_eq(tmp1, tmp2));
e = a;
}
}
bool array_rewriter::has_index_set(expr* e, expr_ref& e0, vector<expr_ref_vector>& indices) {
expr_ref_vector args(m());
expr_ref a(m()), v(m());
a = e;
while (m_util.is_store_ext(e, a, args, v)) {
indices.push_back(args);
e = a;
}
e0 = e;
if (is_lambda(e0)) {
quantifier* q = to_quantifier(e0);
e = q->get_expr();
unsigned num_idxs = q->get_num_decls();
expr* e1, *e2, *e3;
ptr_vector<expr> eqs;
while (!is_ground(e) && m().is_ite(e, e1, e2, e3) && is_ground(e2)) {
args.reset();
args.resize(num_idxs, nullptr);
eqs.reset();
eqs.push_back(e1);
for (unsigned i = 0; i < eqs.size(); ++i) {
expr* e = eqs[i];
if (m().is_and(e)) {
eqs.append(to_app(e)->get_num_args(), to_app(e)->get_args());
}
else if (m().is_eq(e, e1, e2)) {
if (is_var(e2)) {
std::swap(e1, e2);
}
if (is_var(e1) && is_ground(e2)) {
unsigned idx = to_var(e1)->get_idx();
args[num_idxs - idx - 1] = e2;
}
else {
return false;
}
}
}
for (unsigned i = 0; i < num_idxs; ++i) {
if (!args.get(i)) return false;
}
indices.push_back(args);
e = e3;
}
e0 = e;
return is_ground(e);
}
return true;
}
br_status array_rewriter::mk_eq_core(expr * lhs, expr * rhs, expr_ref & result) {
if (!m_expand_store_eq) {
return BR_FAILED;
}
expr_ref_vector fmls(m());
#if 0
// lambda friendly version of array equality rewriting.
vector<expr_ref_vector> indices;
expr_ref lhs0(m()), rhs0(m());
expr_ref tmp1(m()), tmp2(m());
if (has_index_set(lhs, lhs0, indices) && has_index_set(rhs, rhs0, indices) && lhs0 == rhs0) {
expr_ref_vector args(m());
for (auto const& idxs : indices) {
args.reset();
args.push_back(lhs);
args.append(idxs);
mk_select(args.size(), args.c_ptr(), tmp1);
args[0] = rhs;
mk_select(args.size(), args.c_ptr(), tmp2);
fmls.push_back(m().mk_eq(tmp1, tmp2));
}
}
#endif
expr* lhs1 = lhs;
while (m_util.is_store(lhs1)) {
lhs1 = to_app(lhs1)->get_arg(0);
@ -404,25 +490,9 @@ br_status array_rewriter::mk_eq_core(expr * lhs, expr * rhs, expr_ref & result)
if (lhs1 != rhs1) {
return BR_FAILED;
}
ptr_buffer<expr> fmls, args;
expr* e;
expr_ref tmp1(m()), tmp2(m());
#define MK_EQ() \
while (m_util.is_store(e)) { \
args.push_back(lhs); \
args.append(to_app(e)->get_num_args()-2,to_app(e)->get_args()+1); \
mk_select(args.size(), args.c_ptr(), tmp1); \
args[0] = rhs; \
mk_select(args.size(), args.c_ptr(), tmp2); \
fmls.push_back(m().mk_eq(tmp1, tmp2)); \
e = to_app(e)->get_arg(0); \
args.reset(); \
} \
e = lhs;
MK_EQ();
e = rhs;
MK_EQ();
mk_eq(lhs, lhs, rhs, fmls);
mk_eq(rhs, lhs, rhs, fmls);
result = m().mk_and(fmls.size(), fmls.c_ptr());
return BR_REWRITE_FULL;
}

2
src/ast/rewriter/array_rewriter.h
View file

@ -35,6 +35,8 @@ class array_rewriter {
bool m_expand_select_ite;
template<bool CHECK_DISEQ>
lbool compare_args(unsigned num_args, expr * const * args1, expr * const * args2);
bool has_index_set(expr* e, expr_ref& e0, vector<expr_ref_vector>& indices);
void mk_eq(expr* e, expr* lhs, expr* rhs, expr_ref_vector& fmls);
public:
array_rewriter(ast_manager & m, params_ref const & p = params_ref()):
m_util(m) {