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bugfix for float rounding to integral values for cases where ebits >= sbits

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Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
This commit is contained in:
Christoph M. Wintersteiger 2013-11-15 17:19:41 +00:00
parent c96f7b5a51
commit 31495bb9d9
1 changed files with 18 additions and 5 deletions
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23
src/tactic/fpa/fpa2bv_converter.cpp
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@ -1588,8 +1588,7 @@ void fpa2bv_converter::mk_round_to_integral(func_decl * f, unsigned num, expr *
v2 = x;
unsigned ebits = m_util.get_ebits(f->get_range());
unsigned sbits = m_util.get_sbits(f->get_range());
SASSERT(ebits < sbits);
unsigned sbits = m_util.get_sbits(f->get_range());
expr_ref a_sgn(m), a_sig(m), a_exp(m), a_lz(m);
unpack(x, a_sgn, a_sig, a_exp, a_lz, true);
@ -1619,9 +1618,22 @@ void fpa2bv_converter::mk_round_to_integral(func_decl * f, unsigned num, expr *
expr_ref shift(m), r_shifted(m), l_shifted(m);
shift = m_bv_util.mk_bv_sub(m_bv_util.mk_numeral(sbits-1, ebits+1),
m_bv_util.mk_sign_extend(1, a_exp));
r_shifted = m_bv_util.mk_bv_lshr(a_sig, m_bv_util.mk_zero_extend(sbits-ebits-1, shift));
if (sbits > (ebits+1))
r_shifted = m_bv_util.mk_bv_lshr(a_sig, m_bv_util.mk_zero_extend(sbits-(ebits+1), shift));
else if (sbits < (ebits+1))
r_shifted = m_bv_util.mk_extract(ebits, ebits-sbits+1, m_bv_util.mk_bv_lshr(m_bv_util.mk_zero_extend(ebits+1-sbits, a_sig), shift));
else // sbits == ebits+1
r_shifted = m_bv_util.mk_bv_lshr(a_sig, shift);
SASSERT(is_well_sorted(m, r_shifted));
SASSERT(m_bv_util.get_bv_size(r_shifted) == sbits);
l_shifted = m_bv_util.mk_bv_shl(r_shifted, m_bv_util.mk_zero_extend(sbits-ebits-1, shift));
if (sbits > (ebits+1))
l_shifted = m_bv_util.mk_bv_shl(r_shifted, m_bv_util.mk_zero_extend(sbits-(ebits+1), shift));
else if (sbits < (ebits+1))
l_shifted = m_bv_util.mk_extract(ebits, ebits-sbits+1, m_bv_util.mk_bv_shl(m_bv_util.mk_zero_extend(ebits+1-sbits, r_shifted), shift));
else // sbits == ebits+1
l_shifted = m_bv_util.mk_bv_shl(r_shifted, shift);
SASSERT(is_well_sorted(m, l_shifted));
SASSERT(m_bv_util.get_bv_size(l_shifted) == sbits);
res_sig = m_bv_util.mk_concat(m_bv_util.mk_numeral(0, 1),
@ -2239,7 +2251,7 @@ void fpa2bv_converter::mk_bias(expr * e, expr_ref & result) {
void fpa2bv_converter::mk_unbias(expr * e, expr_ref & result) {
unsigned ebits = m_bv_util.get_bv_size(e);
SASSERT(ebits >= 2);
SASSERT(ebits >= 3);
expr_ref e_plus_one(m);
e_plus_one = m_bv_util.mk_bv_add(e, m_bv_util.mk_numeral(1, ebits));
@ -2275,6 +2287,7 @@ void fpa2bv_converter::unpack(expr * e, expr_ref & sgn, expr_ref & sig, expr_ref
expr_ref denormal_sig(m), denormal_exp(m);
denormal_sig = m_bv_util.mk_zero_extend(1, sig);
SASSERT(ebits >= 3); // Note: when ebits=2 there is no 1-exponent, so mk_unbias will produce a 0.
denormal_exp = m_bv_util.mk_numeral(1, ebits);
mk_unbias(denormal_exp, denormal_exp);
dbg_decouple("fpa2bv_unpack_denormal_exp", denormal_exp);