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Re: R: R: About hardfloat in ppc
From: |
Richard Henderson |
Subject: |
Re: R: R: About hardfloat in ppc |
Date: |
Wed, 29 Apr 2020 19:18:52 -0700 |
User-agent: |
Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.7.0 |
On 4/29/20 5:20 PM, 罗勇刚(Yonggang Luo) wrote:
> Question, in hard-float, if we don't want to read the fp register.
> for example: If we wanna compute c = a + b in fp32
> if c = a + b In hard float
> and if b1 = c - a in hard float
> if b1 != b at bitwise level, the we se the inexat to 1, otherwsie
> we set inexat bit to 0? are this valid?
>
> we can also do it for a * b, a - b, a / b.
>
That does seem plausible, for all of the normal values for which we would apply
the hard-float optimization anyway. But we already check for the exceptional
cases:
if (unlikely(f32_is_inf(ur))) {
s->float_exception_flags |= float_flag_overflow;
} else if (unlikely(fabsf(ur.h) <= FLT_MIN)) {
if (post == NULL || post(ua, ub)) {
goto soft;
}
}
r~
- Re: About hardfloat in ppc, (continued)
- Re: About hardfloat in ppc, Yonggang Luo, 2020/04/28
- R: About hardfloat in ppc, Dino Papararo, 2020/04/29
- R: About hardfloat in ppc, Dino Papararo, 2020/04/29
- Re: R: About hardfloat in ppc, Alex Bennée, 2020/04/29
- Re: R: About hardfloat in ppc, Yonggang Luo, 2020/04/29
- Re: R: About hardfloat in ppc, Alex Bennée, 2020/04/29
- R: R: About hardfloat in ppc, Dino Papararo, 2020/04/29
- Re: R: About hardfloat in ppc, Peter Maydell, 2020/04/29
- Re: R: R: About hardfloat in ppc, Alex Bennée, 2020/04/29
- Re: R: R: About hardfloat in ppc, Yonggang Luo, 2020/04/29
- Re: R: R: About hardfloat in ppc,
Richard Henderson <=
- Re: R: R: About hardfloat in ppc, Yonggang Luo, 2020/04/30
- Re: R: R: About hardfloat in ppc, Alex Bennée, 2020/04/30
- Re: R: R: About hardfloat in ppc, Yonggang Luo, 2020/04/30
- Re: R: R: About hardfloat in ppc, BALATON Zoltan, 2020/04/30
- R: R: R: About hardfloat in ppc, Dino Papararo, 2020/04/30
- Re: About hardfloat in ppc, Programmingkid, 2020/04/30
- Re: About hardfloat in ppc, Yonggang Luo, 2020/04/30
- Re: R: About hardfloat in ppc, Yonggang Luo, 2020/04/29
- Re: About hardfloat in ppc, BALATON Zoltan, 2020/04/30
- Re: About hardfloat in ppc, Alex Bennée, 2020/04/30