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Fix for corner-case in fp.roundToIntegral. Fixes #2894.

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This commit is contained in:
Christoph M. Wintersteiger 2020-07-16 11:58:18 +00:00
parent c321fb7726
commit ccdae7af24
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GPG key ID: BCF6360F86294467
1 changed files with 11 additions and 3 deletions
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14
src/ast/fpa/fpa2bv_converter.cpp
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@ -2049,7 +2049,7 @@ void fpa2bv_converter::mk_round_to_integral(sort * s, expr_ref & rm, expr_ref &
expr_ref shift(m), shifted_sig(m), div(m), rem(m);
shift = m_bv_util.mk_bv_sub(m_bv_util.mk_numeral(sbits - 1, sbits),
m_bv_util.mk_zero_extend(sbits-ebits, a_exp));
m_bv_util.mk_sign_extend(sbits-ebits, a_exp));
shifted_sig = m_bv_util.mk_bv_lshr(m_bv_util.mk_concat(a_sig, zero_s),
m_bv_util.mk_concat(zero_s, shift));
div = m_bv_util.mk_extract(2*sbits-1, sbits, shifted_sig);
@ -2107,6 +2107,11 @@ void fpa2bv_converter::mk_round_to_integral(sort * s, expr_ref & rm, expr_ref &
c52 = rm_is_rtp;
c53 = rm_is_rtn;
dbg_decouple("fpa2bv_r2i_c51", c51);
dbg_decouple("fpa2bv_r2i_c52", c52);
dbg_decouple("fpa2bv_r2i_c53", c53);
dbg_decouple("fpa2bv_r2i_c531", c531);
res_sig = div;
m_simp.mk_ite(c53, v53, res_sig, res_sig);
m_simp.mk_ite(c52, v52, res_sig, res_sig);
@ -2132,12 +2137,15 @@ void fpa2bv_converter::mk_round_to_integral(sort * s, expr_ref & rm, expr_ref &
min_exp = m_bv_util.mk_sign_extend(2, min_exp);
mk_leading_zeros(res_sig, ebits+2, sig_lz);
max_exp_delta = m_bv_util.mk_bv_sub(res_exp, min_exp);
sig_lz_capped = m.mk_ite(m_bv_util.mk_sle(sig_lz, max_exp_delta), sig_lz, max_exp_delta);
renorm_delta = m.mk_ite(m_bv_util.mk_sle(zero_e2, sig_lz_capped), sig_lz_capped, zero_e2);
sig_lz_capped = m.mk_ite(m_bv_util.mk_ule(sig_lz, max_exp_delta), sig_lz, max_exp_delta);
renorm_delta = m.mk_ite(m_bv_util.mk_ule(zero_e2, sig_lz_capped), sig_lz_capped, zero_e2);
SASSERT(m_bv_util.get_bv_size(renorm_delta) == ebits + 2);
res_exp = m_bv_util.mk_bv_sub(res_exp, renorm_delta);
res_sig = m_bv_util.mk_bv_shl(res_sig, m_bv_util.mk_zero_extend(sbits-ebits-2, renorm_delta));
dbg_decouple("fpa2bv_r2i_renorm_delta", renorm_delta);
dbg_decouple("fpa2bv_r2i_sig_lz", sig_lz);
dbg_decouple("fpa2bv_r2i_sig_lz_capped", sig_lz_capped);
dbg_decouple("fpa2bv_r2i_max_exp_delta", max_exp_delta);
res_exp = m_bv_util.mk_extract(ebits-1, 0, res_exp);
mk_bias(res_exp, res_exp);