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Bugfix for fp.fma. One piece of puzzle #872.

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This commit is contained in:
Christoph M. Wintersteiger 2017-07-21 21:12:45 +01:00
parent faa19117e4
commit 0f1583309d
1 changed files with 29 additions and 6 deletions
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35
src/ast/fpa/fpa2bv_converter.cpp
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@ -1632,8 +1632,6 @@ void fpa2bv_converter::mk_fma(func_decl * f, unsigned num, expr * const * args,
res_exp = e_exp;
// Result could overflow into 4.xxx ...
family_id bvfid = m_bv_util.get_fid();
expr_ref res_sgn_c1(m), res_sgn_c2(m), res_sgn_c3(m);
expr_ref not_e_sgn(m), not_f_sgn(m), not_sign_bv(m);
@ -1646,11 +1644,34 @@ void fpa2bv_converter::mk_fma(func_decl * f, unsigned num, expr * const * args,
expr * res_sgn_or_args[3] = { res_sgn_c1, res_sgn_c2, res_sgn_c3 };
res_sgn = m_bv_util.mk_bv_or(3, res_sgn_or_args);
// Result could have overflown into 4.xxx.
SASSERT(m_bv_util.get_bv_size(sig_abs) == 2 * sbits + 2);
expr_ref ovfl_into_4(m);
ovfl_into_4 = m.mk_eq(m_bv_util.mk_extract(2 * sbits + 1, 2 * sbits, sig_abs),
m_bv_util.mk_numeral(1, 2));
dbg_decouple("fpa2bv_fma_ovfl_into_4", ovfl_into_4);
if (sbits > 5) {
sticky_raw = m_bv_util.mk_extract(sbits - 5, 0, sig_abs);
sticky = m_bv_util.mk_zero_extend(sbits + 3, m.mk_app(bvfid, OP_BREDOR, sticky_raw.get()));
expr * res_or_args[2] = { m_bv_util.mk_extract(2 * sbits - 1, sbits - 4, sig_abs), sticky };
res_sig = m_bv_util.mk_bv_or(2, res_or_args);
expr_ref sticky_raw(m), sig_upper(m), sticky_redd(m), res_sig_norm(m);
sticky_raw = m_bv_util.mk_extract(sbits - 4, 0, sig_abs);
sig_upper = m_bv_util.mk_extract(2 * sbits, sbits - 3, sig_abs);
SASSERT(m_bv_util.get_bv_size(sig_upper) == sbits + 4);
sticky_redd = m.mk_app(bvfid, OP_BREDOR, sticky_raw.get());
sticky = m_bv_util.mk_zero_extend(sbits + 3, sticky_redd);
expr * res_or_args[2] = { sig_upper, sticky };
res_sig_norm = m_bv_util.mk_bv_or(2, res_or_args);
expr_ref sticky_raw_ovfl(m), sig_upper_ovfl(m), sticky_redd_ovfl(m), sticky_ovfl(m), res_sig_ovfl(m);
sticky_raw_ovfl = m_bv_util.mk_extract(sbits - 4, 0, sig_abs);
sig_upper_ovfl = m_bv_util.mk_extract(2 * sbits, sbits - 3, sig_abs);
SASSERT(m_bv_util.get_bv_size(sig_upper_ovfl) == sbits + 4);
sticky_redd_ovfl = m.mk_app(bvfid, OP_BREDOR, sticky_raw_ovfl.get());
sticky_ovfl = m_bv_util.mk_zero_extend(sbits + 3, sticky_redd_ovfl);
expr * res_or_args_ovfl[2] = { sig_upper_ovfl, sticky_ovfl };
res_sig_ovfl = m_bv_util.mk_bv_or(2, res_or_args_ovfl);
res_sig = m.mk_ite(ovfl_into_4, res_sig_ovfl, res_sig_norm);
res_exp = m.mk_ite(ovfl_into_4, m_bv_util.mk_bv_add(res_exp, m_bv_util.mk_numeral(1, ebits+2)),
res_exp);
}
else {
unsigned too_short = 6 - sbits;
@ -1658,6 +1679,8 @@ void fpa2bv_converter::mk_fma(func_decl * f, unsigned num, expr * const * args,
res_sig = m_bv_util.mk_extract(sbits + 3, 0, sig_abs);
}
dbg_decouple("fpa2bv_fma_add_sum_sticky", sticky);
dbg_decouple("fpa2bv_fma_sig_abs", sig_abs);
dbg_decouple("fpa2bv_fma_res_sig", res_sig);
SASSERT(m_bv_util.get_bv_size(res_sig) == sbits + 4);
expr_ref is_zero_sig(m), nil_sbits4(m);