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bugfixes for float to float conversion

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Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
This commit is contained in:
Christoph M. Wintersteiger 2013-11-14 20:13:37 +00:00
parent b77d408128
commit c96f7b5a51
1 changed files with 22 additions and 14 deletions
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36
src/tactic/fpa/fpa2bv_converter.cpp
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@ -1831,8 +1831,8 @@ void fpa2bv_converter::mk_to_float(func_decl * f, unsigned num, expr * const * a
rm = args[0];
x = args[1];
unsigned from_sbits = m_util.get_sbits(m.get_sort(args[1]));
unsigned from_ebits = m_util.get_ebits(m.get_sort(args[1]));
unsigned from_sbits = m_util.get_sbits(m.get_sort(x));
unsigned from_ebits = m_util.get_ebits(m.get_sort(x));
unsigned to_sbits = m_util.get_sbits(s);
unsigned to_ebits = m_util.get_ebits(s);
@ -1911,7 +1911,12 @@ void fpa2bv_converter::mk_to_float(func_decl * f, unsigned num, expr * const * a
if (from_ebits < (to_ebits + 2))
{
res_exp = m_bv_util.mk_sign_extend(to_ebits-from_ebits+2, exp);
res_exp = m_bv_util.mk_sign_extend(to_ebits-from_ebits+2, exp);
// subtract lz for subnormal numbers.
expr_ref lz_ext(m);
lz_ext = m_bv_util.mk_zero_extend(to_ebits-from_ebits+2, lz);
res_exp = m_bv_util.mk_bv_sub(res_exp, lz_ext);
}
else if (from_ebits > (to_ebits + 2))
{
@ -1936,30 +1941,33 @@ void fpa2bv_converter::mk_to_float(func_decl * f, unsigned num, expr * const * a
// Note: Upon overflow, we _could_ try to shift the significand around...
res_exp = low;
}
else
res_exp = exp;
// subtract lz for subnormal numbers.
expr_ref lz_ext(m), lz_rest(m), lz_redor(m), lz_redor_bool(m);
lz_ext = m_bv_util.mk_extract(to_ebits+1, 0, lz);
lz_rest = m_bv_util.mk_extract(from_ebits-1, to_ebits+2, lz);
lz_redor = m.mk_app(m_bv_util.get_fid(), OP_BREDOR, lz_rest.get());
m_simp.mk_eq(lz_redor, one1, lz_redor_bool);
m_simp.mk_or(exponent_overflow, lz_redor_bool, exponent_overflow);
res_exp = m_bv_util.mk_bv_sub(low, lz_ext);
}
else // from_ebits == (to_ebits + 2)
res_exp = m_bv_util.mk_bv_sub(exp, lz);
// subtract lz for subnormal numbers.
expr_ref lz_ext(m);
lz_ext = m_bv_util.mk_zero_extend(to_ebits-from_ebits+2, lz);
res_exp = m_bv_util.mk_bv_sub(res_exp, lz_ext);
SASSERT(m_bv_util.get_bv_size(res_exp) == to_ebits+2);
SASSERT(is_well_sorted(m, res_exp));
dbg_decouple("fpa2bv_to_float_res_sig", res_sig);
dbg_decouple("fpa2bv_to_float_res_exp", res_exp);
expr_ref rounded(m);
round(s, rm, res_sgn, res_sig, res_exp, rounded);
round(s, rm, res_sgn, res_sig, res_exp, rounded);
expr_ref is_neg(m), sig_inf(m);
m_simp.mk_eq(sgn, one1, is_neg);
mk_ite(is_neg, ninf, pinf, sig_inf);
dbg_decouple("fpa2bv_to_float_exp_ovf", exponent_overflow);
mk_ite(exponent_overflow, sig_inf, rounded, v6);
// And finally, we tie them together.