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Throw proper warning instead of assertion violation in fp.rem. Fixes #2934.

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Christoph M. Wintersteiger 2020-02-25 17:17:41 +00:00
parent 198622b61a
commit 963f8240c2
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GPG key ID: BCF6360F86294467
1 changed files with 46 additions and 12 deletions
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58
src/ast/fpa/fpa2bv_converter.cpp
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@ -1106,13 +1106,9 @@ void fpa2bv_converter::mk_rem(sort * s, expr_ref & x, expr_ref & y, expr_ref & r
const mpz & two_to_ebits = fu().fm().m_powers2(ebits);
mpz max_exp_diff;
m_mpz_manager.sub(two_to_ebits, 3, max_exp_diff);
SASSERT(m_mpz_manager.is_int64(max_exp_diff));
SASSERT(m_mpz_manager.get_uint64(max_exp_diff) <= UINT_MAX);
uint64_t max_exp_diff_ui64 = m_mpz_manager.get_uint64(max_exp_diff);
SASSERT(max_exp_diff_ui64 <= UINT_MAX);
unsigned max_exp_diff_ui = (unsigned)max_exp_diff_ui64;
m_mpz_manager.del(max_exp_diff);
if (m_mpz_manager.gt(max_exp_diff, INT32_MAX))
// because zero-extend allows only int params...
throw rewriter_exception("Maximum exponent difference in fp.rem does not fit into a signed int. Huge exponents in fp.rem are not supported.");
expr_ref a_exp_ext(m), b_exp_ext(m);
a_exp_ext = m_bv_util.mk_sign_extend(2, a_exp);
@ -1136,16 +1132,54 @@ void fpa2bv_converter::mk_rem(sort * s, expr_ref & x, expr_ref & y, expr_ref & r
// but calculating this via rem = x - y * nearest(x/y) creates huge
// circuits, too. Lazy instantiation seems the way to go in the long run
// (using the lazy bit-blaster helps on simple instances).
expr_ref a_sig_ext(m), b_sig_ext(m), lshift(m), rshift(m), shifted(m), huge_rem(m), huge_div(m), huge_div_is_even(m);
a_sig_ext = m_bv_util.mk_concat(m_bv_util.mk_zero_extend(max_exp_diff_ui, a_sig), m_bv_util.mk_numeral(0, 3));
b_sig_ext = m_bv_util.mk_concat(m_bv_util.mk_zero_extend(max_exp_diff_ui, b_sig), m_bv_util.mk_numeral(0, 3));
lshift = m_bv_util.mk_zero_extend(max_exp_diff_ui + sbits - (ebits+2) + 3, exp_diff);
rshift = m_bv_util.mk_zero_extend(max_exp_diff_ui + sbits - (ebits+2) + 3, neg_exp_diff);
expr_ref lshift(m), rshift(m), shifted(m), huge_rem(m), huge_div(m), huge_div_is_even(m);
expr_ref a_sig_ext_l = a_sig, b_sig_ext_l = b_sig;
mpz remaining;
m_mpz_manager.set(remaining, max_exp_diff);
while (m_mpz_manager.gt(remaining, INT32_MAX)) {
SASSERT(false); // zero-extend ast's expect int params which would overflow.
a_sig_ext_l = m_bv_util.mk_zero_extend(INT32_MAX, a_sig_ext_l);
b_sig_ext_l = m_bv_util.mk_zero_extend(INT32_MAX, b_sig_ext_l);
m_mpz_manager.sub(remaining, INT32_MAX, remaining);
}
if (!m_mpz_manager.is_zero(remaining)) {
unsigned rn = m_mpz_manager.get_uint(remaining);
a_sig_ext_l = m_bv_util.mk_zero_extend(rn, a_sig_ext_l);
b_sig_ext_l = m_bv_util.mk_zero_extend(rn, b_sig_ext_l);
}
expr_ref a_sig_ext(m), b_sig_ext(m);
a_sig_ext = m_bv_util.mk_concat(a_sig_ext_l, m_bv_util.mk_numeral(0, 3));
b_sig_ext = m_bv_util.mk_concat(b_sig_ext_l, m_bv_util.mk_numeral(0, 3));
mpz max_exp_diff_adj;
m_mpz_manager.add(max_exp_diff, sbits, max_exp_diff_adj);
m_mpz_manager.sub(max_exp_diff_adj, ebits, max_exp_diff_adj);
m_mpz_manager.add(max_exp_diff_adj, 1, max_exp_diff_adj);
expr_ref edr_tmp = exp_diff, nedr_tmp = neg_exp_diff;
m_mpz_manager.set(remaining, max_exp_diff_adj);
while (m_mpz_manager.gt(remaining, INT32_MAX)) {
SASSERT(false); // zero-extend ast's expect int params which would overflow.
edr_tmp = m_bv_util.mk_zero_extend(INT32_MAX, edr_tmp);
nedr_tmp = m_bv_util.mk_zero_extend(INT32_MAX, nedr_tmp);
m_mpz_manager.sub(remaining, INT32_MAX, remaining);
}
if (!m_mpz_manager.is_zero(remaining)) {
edr_tmp = m_bv_util.mk_zero_extend(m_mpz_manager.get_uint(remaining), edr_tmp);
nedr_tmp = m_bv_util.mk_zero_extend(m_mpz_manager.get_uint(remaining), nedr_tmp);
}
lshift = edr_tmp;
rshift = nedr_tmp;
m_mpz_manager.del(remaining);
m_mpz_manager.del(max_exp_diff);
m_mpz_manager.del(max_exp_diff_adj);
shifted = m.mk_ite(exp_diff_is_neg, m_bv_util.mk_bv_ashr(a_sig_ext, rshift),
m_bv_util.mk_bv_shl(a_sig_ext, lshift));
huge_rem = m_bv_util.mk_bv_urem(shifted, b_sig_ext);
huge_div = m.mk_app(m_bv_util.get_fid(), OP_BUDIV_I, shifted, b_sig_ext);
huge_div_is_even = m.mk_eq(m_bv_util.mk_extract(0, 0, huge_div), m_bv_util.mk_numeral(0, 1));
SASSERT(is_well_sorted(m, huge_rem));
dbg_decouple("fpa2bv_rem_exp_diff_is_neg", exp_diff_is_neg);
dbg_decouple("fpa2bv_rem_lshift", lshift);
dbg_decouple("fpa2bv_rem_rshift", rshift);