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add rewrites for #2575
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Signed-off-by: Nikolaj Bjorner <[email protected]>
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@NikolajBjorner
NikolajBjorner committed Sep 20, 2019
1 parent 80636dd commit cd0cd82
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Showing 4 changed files with 77 additions and 20 deletions.
83 changes: 65 additions & 18 deletions src/ast/rewriter/seq_rewriter.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -441,7 +441,7 @@ br_status seq_rewriter::mk_app_core(func_decl * f, unsigned num_args, expr * con
st = mk_re_complement(args[0], result);
break;
case OP_RE_LOOP:
st = mk_re_loop(num_args, args, result);
st = mk_re_loop(f, num_args, args, result);
break;
case OP_RE_EMPTY_SET:
return BR_FAILED;
Expand Down Expand Up @@ -1682,27 +1682,41 @@ br_status seq_rewriter::mk_re_concat(expr* a, expr* b, expr_ref& result) {
result = m_util.re.mk_concat(b, a);
return BR_DONE;
}
{
unsigned lo1, hi1, lo2, hi2;
if (m_util.re.is_loop(a, a1, lo1, hi1) && m_util.re.is_loop(b, b1, lo2, hi2) && a1 == b1) {
result = m_util.re.mk_loop(a1, lo1 + lo2, hi1 + hi2);
unsigned lo1, hi1, lo2, hi2;

if (m_util.re.is_loop(a, a1, lo1, hi1) && m_util.re.is_loop(b, b1, lo2, hi2) && a1 == b1) {
SASSERT(lo1 <= hi1 && lo2 <= hi2);
result = m_util.re.mk_loop(a1, lo1 + lo2, hi1 + hi2);
return BR_DONE;
}
if (m_util.re.is_loop(a, a1, lo1) && m_util.re.is_loop(b, b1, lo2) && a1 == b1) {
result = m_util.re.mk_loop(a1, lo1 + lo2);
return BR_DONE;
}
for (unsigned i = 0; i < 2; ++i) {
// (loop a lo1) + (loop a lo2 hi2) = (loop a lo1 + lo2)
if (m_util.re.is_loop(a, a1, lo1) && m_util.re.is_loop(b, b1, lo2, hi2) && a1 == b1) {
SASSERT(lo2 <= hi2);
result = m_util.re.mk_loop(a1, lo1 + lo2);
return BR_DONE;
}
if (m_util.re.is_loop(a, a1, lo1) && m_util.re.is_loop(b, b1, lo2) && a1 == b1) {
result = m_util.re.mk_loop(a1, lo1 + lo2);
// (loop a lo1 hi1) + a* = (loop a lo1)
if (m_util.re.is_loop(a, a1, lo1, hi1) && m_util.re.is_star(b, b1) && a1 == b1) {
result = m_util.re.mk_loop(a1, lo1);
return BR_DONE;
}
}
{
expr* lo1, *hi1, *lo2, *hi2;
if (m_util.re.is_loop(a, a1, lo1, hi1) && m_util.re.is_loop(b, b1, lo2, hi2) && a1 == b1) {
result = m_util.re.mk_loop(a1, m_autil.mk_add(lo1, lo2), m_autil.mk_add(hi1, hi2));
// (loop a lo1) + a* = (loop a lo1)
if (m_util.re.is_loop(a, a1, lo1) && m_util.re.is_star(b, b1) && a1 == b1) {
result = a;
return BR_DONE;
}
if (m_util.re.is_loop(a, a1, lo1) && m_util.re.is_loop(b, b1, lo2) && a1 == b1) {
result = m_util.re.mk_loop(a1, m_autil.mk_add(lo1, lo2));
// (loop a lo1 hi1) + a = (loop a lo1+1 hi1+1)
if (m_util.re.is_loop(a, a1, lo1, hi1) && a1 == b) {
SASSERT(lo1 <= hi1);
result = m_util.re.mk_loop(a1, lo1+1, hi1+1);
return BR_DONE;
}
std::swap(a, b);
}
return BR_FAILED;
}
Expand Down Expand Up @@ -1804,22 +1818,55 @@ br_status seq_rewriter::mk_re_inter(expr* a, expr* b, expr_ref& result) {
}


br_status seq_rewriter::mk_re_loop(unsigned num_args, expr* const* args, expr_ref& result) {
br_status seq_rewriter::mk_re_loop(func_decl* f, unsigned num_args, expr* const* args, expr_ref& result) {
rational n1, n2;
unsigned lo, hi;
expr* a = nullptr;
switch (num_args) {
case 1:
// (loop (loop a lo hi) lo2 hi2) = (loop lo*lo2 hi*hi2)
if (m_util.re.is_loop(args[0], a, lo, hi) && f->get_num_parameters() == 2) {
result = m_util.re.mk_loop(a, f->get_parameter(0).get_int() * lo, f->get_parameter(1).get_int() * hi);
return BR_REWRITE1;
}
// (loop (loop a lo hi) lo2) = (loop lo*lo2)
if (m_util.re.is_loop(args[0], a, lo, hi) && f->get_num_parameters() == 1) {
result = m_util.re.mk_loop(a, f->get_parameter(0).get_int() * lo);
return BR_REWRITE1;
}
// (loop (loop a lo) lo2 ..) = (loop lo*lo2)
if (m_util.re.is_loop(args[0], a, lo)) {
SASSERT(f->get_num_parameters() >= 1);
result = m_util.re.mk_loop(a, f->get_parameter(0).get_int() * lo);
return BR_REWRITE1;
}
// (loop a 0 0) = ""
if (f->get_num_parameters() == 2 && f->get_parameter(1).get_int() == 0) {
result = m_util.re.mk_to_re(m_util.str.mk_empty(m_util.re.to_seq(m().get_sort(args[0]))));
return BR_DONE;
}
// (loop a 1 1) = a
if (f->get_num_parameters() == 2 && f->get_parameter(0).get_int() == 1 && f->get_parameter(1).get_int() == 1) {
result = args[0];
return BR_DONE;
}
// (loop a 0) = a*
if (f->get_num_parameters() == 1 && f->get_parameter(0).get_int() == 0) {
result = m_util.re.mk_star(args[0]);
return BR_DONE;
}
break;
case 2:
if (m_autil.is_numeral(args[1], n1) && n1.is_unsigned()) {
result = m_util.re.mk_loop(args[0], n1.get_unsigned());
return BR_DONE;
return BR_REWRITE1;
}
break;
case 3:
if (m_autil.is_numeral(args[1], n1) && n1.is_unsigned() &&
m_autil.is_numeral(args[2], n2) && n2.is_unsigned()) {
m_autil.is_numeral(args[2], n2) && n2.is_unsigned() && n1 <= n2) {
result = m_util.re.mk_loop(args[0], n1.get_unsigned(), n2.get_unsigned());
return BR_DONE;
return BR_REWRITE1;
}
break;
default:
Expand Down
2 changes: 1 addition & 1 deletion src/ast/rewriter/seq_rewriter.h
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Original file line number Diff line number Diff line change
Expand Up @@ -133,7 +133,7 @@ class seq_rewriter {
br_status mk_re_star(expr* a, expr_ref& result);
br_status mk_re_plus(expr* a, expr_ref& result);
br_status mk_re_opt(expr* a, expr_ref& result);
br_status mk_re_loop(unsigned num_args, expr* const* args, expr_ref& result);
br_status mk_re_loop(func_decl* f, unsigned num_args, expr* const* args, expr_ref& result);
br_status mk_re_range(expr* lo, expr* hi, expr_ref& result);

bool cannot_contain_prefix(expr* a, expr* b);
Expand Down
8 changes: 8 additions & 0 deletions src/ast/seq_decl_plugin.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -747,6 +747,9 @@ func_decl * seq_decl_plugin::mk_func_decl(decl_kind k, unsigned num_parameters,
if (num_parameters == 0 || num_parameters > 2 || !parameters[0].is_int() || (num_parameters == 2 && !parameters[1].is_int())) {
m.raise_exception("Expecting two numeral parameters to function re-loop");
}
if (num_parameters == 2 && parameters[0].get_int() > parameters[1].get_int()) {
m.raise_exception("Lower bound cannot be higher than upper bound in loop specfication");
}
return m.mk_func_decl(m_sigs[k]->m_name, arity, domain, rng, func_decl_info(m_family_id, k, num_parameters, parameters));
case 2:
if (m_re != domain[0] || !arith_util(m).is_int(domain[1])) {
Expand Down Expand Up @@ -1083,6 +1086,11 @@ app* seq_util::str::mk_is_empty(expr* s) const {
}


sort* seq_util::re::to_seq(sort* re) {
SASSERT(u.is_re(re));
return to_sort(re->get_parameter(0).get_ast());
}

app* seq_util::re::mk_loop(expr* r, unsigned lo) {
parameter param(lo);
return m.mk_app(m_fid, OP_RE_LOOP, 1, &param, 1, &r);
Expand Down
4 changes: 3 additions & 1 deletion src/ast/seq_decl_plugin.h
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Original file line number Diff line number Diff line change
Expand Up @@ -348,11 +348,13 @@ class seq_util {

class re {
ast_manager& m;
seq_util& u;
family_id m_fid;
public:
re(seq_util& u): m(u.m), m_fid(u.m_fid) {}
re(seq_util& u): u(u), m(u.m), m_fid(u.m_fid) {}

sort* mk_re(sort* seq) { parameter param(seq); return m.mk_sort(m_fid, RE_SORT, 1, &param); }
sort* to_seq(sort* re);

app* mk_to_re(expr* s) { return m.mk_app(m_fid, OP_SEQ_TO_RE, 1, &s); }
app* mk_in_re(expr* s, expr* r) { return m.mk_app(m_fid, OP_SEQ_IN_RE, s, r); }
Expand Down

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