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FPA: fixes for sbits < ebits

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Signed-off-by: Christoph M. Wintersteiger <cwinter@microsoft.com>
This commit is contained in:
Christoph M. Wintersteiger 2013-01-11 11:15:18 +00:00
parent dd127c2f71
commit 61b686f86f
1 changed files with 11 additions and 9 deletions
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20
src/tactic/fpa/fpa2bv_converter.cpp
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@ -237,15 +237,14 @@ void fpa2bv_converter::mk_pzero(func_decl *f, expr_ref & result) {
void fpa2bv_converter::add_core(unsigned sbits, unsigned ebits, expr_ref & rm,
expr_ref & c_sgn, expr_ref & c_sig, expr_ref & c_exp, expr_ref & d_sgn, expr_ref & d_sig, expr_ref & d_exp,
expr_ref & res_sgn, expr_ref & res_sig, expr_ref & res_exp)
{
{
// c/d are now such that c_exp >= d_exp.
expr_ref exp_delta(m);
exp_delta = m_bv_util.mk_bv_sub(c_exp, d_exp);
dbg_decouple("fpa2bv_add_exp_delta", exp_delta);
// cap the delta
// cap the delta
expr_ref cap(m);
cap = m_bv_util.mk_numeral(sbits+2, ebits);
m_simp.mk_ite(m_bv_util.mk_ule(cap, exp_delta), cap, exp_delta, exp_delta);
@ -404,8 +403,7 @@ void fpa2bv_converter::mk_add(func_decl * f, unsigned num, expr * const * args,
// Actual addition.
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), b_sgn(m), b_sig(m), b_exp(m);
unpack(x, a_sgn, a_sig, a_exp, true);
@ -1636,7 +1634,6 @@ void fpa2bv_converter::unpack(expr * e, expr_ref & sgn, expr_ref & sig, expr_ref
mk_unbias(denormal_exp, denormal_exp);
if (normalize) {
SASSERT(ebits <= sbits);
expr_ref is_sig_zero(m), shift(m), lz(m);
m_simp.mk_eq(m_bv_util.mk_numeral(0, sbits-1), sig, is_sig_zero);
mk_leading_zeros(sig, ebits, lz);
@ -1644,9 +1641,14 @@ void fpa2bv_converter::unpack(expr * e, expr_ref & sgn, expr_ref & sig, expr_ref
SASSERT(is_well_sorted(m, is_sig_zero));
SASSERT(is_well_sorted(m, lz));
SASSERT(is_well_sorted(m, shift));
denormal_sig = m_bv_util.mk_bv_shl(denormal_sig, m_bv_util.mk_zero_extend(sbits-ebits, shift));
// CMW: The book says we don't need this, but it feels wrong not to do that.
//denormal_exp = m_bv_util.mk_bv_sub(denormal_exp, shift);
if (ebits > sbits) {
expr_ref q(m);
q = m_bv_util.mk_zero_extend(sbits-ebits, shift);
denormal_sig = m_bv_util.mk_bv_shl(denormal_sig, q);
}
else {
denormal_sig = m_bv_util.mk_bv_shl(denormal_sig, shift);
}
}
SASSERT(is_well_sorted(m, normal_sig));