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Fix corner case in MPF FMA (#6075)
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@ -904,8 +904,6 @@ void mpf_manager::fma(mpf_rounding_mode rm, mpf const & x, mpf const & y, mpf co
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SASSERT(m_mpz_manager.lt(res.significand(), m_powers2(2 * x.sbits + 1 + 3)));
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if (m_mpz_manager.ge(res.significand(), m_powers2(2 * x.sbits + 3)))
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{
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SASSERT(exp(res) < mk_max_exp(x.ebits)); // NYI.
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res.get().exponent++;
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renorm_sticky = !m_mpz_manager.is_even(res.significand());
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m_mpz_manager.machine_div2k(res.significand(), 1);
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@ -923,26 +921,32 @@ void mpf_manager::fma(mpf_rounding_mode rm, mpf const & x, mpf const & y, mpf co
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TRACE("mpf_dbg", tout << "R*= " << to_string_binary(res, 2, 0) << " (renormalized, delta=" << renorm_delta << ")" << std::endl;);
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set(o, x.ebits, x.sbits, res.sign(), res.exponent(), mpz(0));
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if (exp(res) <= mk_max_exp(x.ebits))
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{
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set(o, x.ebits, x.sbits, res.sign(), res.exponent(), mpz(0));
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if (x.sbits >= 4) {
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m_mpz_manager.machine_div_rem(res.significand(), m_powers2(x.sbits - 4 + 3), o.significand, sticky_rem);
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renorm_sticky |= !m_mpz_manager.is_zero(sticky_rem);
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if (x.sbits >= 4) {
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m_mpz_manager.machine_div_rem(res.significand(), m_powers2(x.sbits - 4 + 3), o.significand, sticky_rem);
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renorm_sticky |= !m_mpz_manager.is_zero(sticky_rem);
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}
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else {
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m_mpz_manager.mul2k(res.significand(), 4 - x.sbits + 3, o.significand);
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}
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if (renorm_sticky && m_mpz_manager.is_even(o.significand))
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m_mpz_manager.inc(o.significand);
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TRACE("mpf_dbg", tout << "sum[-1:sbits+2] = " << m_mpz_manager.to_string(o.significand) << std::endl;
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tout << "R = " << to_string_binary(o, 1, 3) << std::endl;);
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if (m_mpz_manager.is_zero(o.significand))
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mk_zero(x.ebits, x.sbits, rm == MPF_ROUND_TOWARD_NEGATIVE, o);
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else
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round(rm, o);
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}
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else {
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m_mpz_manager.mul2k(res.significand(), 4 - x.sbits + 3, o.significand);
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mk_inf(x.ebits, x.sbits, res.sign(), o);
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}
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if (renorm_sticky && m_mpz_manager.is_even(o.significand))
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m_mpz_manager.inc(o.significand);
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TRACE("mpf_dbg", tout << "sum[-1:sbits+2] = " << m_mpz_manager.to_string(o.significand) << std::endl;
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tout << "R = " << to_string_binary(o, 1, 3) << std::endl;);
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if (m_mpz_manager.is_zero(o.significand))
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mk_zero(x.ebits, x.sbits, rm == MPF_ROUND_TOWARD_NEGATIVE, o);
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else
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round(rm, o);
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}
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}
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