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add more pre-processing for band

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Signed-off-by: Nikolaj Bjorner <nbjorner@microsoft.com>
This commit is contained in:
Nikolaj Bjorner 2025-11-04 09:45:40 -08:00
parent 4828ed97be
commit daf66e63c6
2 changed files with 34 additions and 12 deletions
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44
src/ast/rewriter/arith_rewriter.cpp
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@ -1642,14 +1642,7 @@ br_status arith_rewriter::mk_band_core(unsigned sz, expr* arg1, expr* arg2, expr
x = mod(x, N);
if (is_num_y)
y = mod(y, N);
if (is_num_x && x.is_zero()) {
result = m_util.mk_int(0);
return BR_DONE;
}
if (is_num_y && y.is_zero()) {
result = m_util.mk_int(0);
return BR_DONE;
}
if (is_num_x && is_num_y) {
rational r(0);
for (unsigned i = 0; i < sz; ++i)
@ -1658,13 +1651,42 @@ br_status arith_rewriter::mk_band_core(unsigned sz, expr* arg1, expr* arg2, expr
result = m_util.mk_int(r);
return BR_DONE;
}
if (is_num_y) {
std::swap(is_num_x, is_num_y);
std::swap(x, y);
std::swap(arg1, arg2);
}
if (is_num_x && x.is_zero()) {
result = m_util.mk_int(0);
return BR_DONE;
}
if (is_num_x && (x + 1).is_power_of_two()) {
result = m_util.mk_mod(arg2, m_util.mk_int(x + 1));
return BR_REWRITE1;
}
if (is_num_y && (y + 1).is_power_of_two()) {
result = m_util.mk_mod(arg1, m_util.mk_int(y + 1));
return BR_REWRITE1;
// x = 2^k*(2^m-1)
// result := y mod 2^{k+m} - y mod 2^k
if (is_num_x) {
unsigned k = x.trailing_zeros();
numeral x1 = div(x, rational::power_of_two(k));
if ((x1 + 1).is_power_of_two()) {
unsigned m = (x1 + 1).trailing_zeros();
rational km = rational::power_of_two(k + m);
result = m_util.mk_mod(arg2, m_util.mk_int(km));
result = m_util.mk_sub(result, m_util.mk_mod(arg2, m_util.mk_int(rational::power_of_two(k))));
return BR_REWRITE3;
}
}
if (arg1 == arg2) {
result = arg1;
return BR_DONE;
}
if (!is_num_x && arg1->get_id() > arg2->get_id()) {
result = m_util.mk_band(sz, arg2, arg1);
return BR_DONE;
}
return BR_FAILED;
}