Ok, thanks for the advice. I have modified __builtin_nanq("") and
__builtin_nansq("") in gcc according to the functionality of the function, and
the implementation is shown in the following code.
>>>
__float128 __nanq (const char * str)
{
union _FP_UNION_Q nan;
nan.bits.frac0 = 0;
nan.bits.frac1 = 0;
nan.bits.exp = 0x7FFF;
nan.bits.sign = 0;
return nan.flt;
}
__float128 __nansq (const char *str)
{
union _FP_UNION_Q nan;
nan.bits.frac0 = 0xFFFFFFFFFFFFFFFFUL;
nan.bits.frac1 = 0x0000FFFFFFFFFFFFUL;
nan.bits.exp = 0x7FFF;
nan.bits.sign = 0;
return nan.flt;
}
-----
> -----原始邮件-----
> 发件人: "Xi Ruoyao" <[email protected]>
> 发送时间:2023-08-08 10:24:39 (星期二)
> 收件人: chenxiaolong <[email protected]>, [email protected]
> 抄送: [email protected], [email protected], [email protected]
> 主题: Re: [PATCH v2] LoongArch:Implement 128-bit floating point functions in
> gcc.
>
> On Tue, 2023-08-08 at 10:09 +0800, chenxiaolong wrote:
> > +/* Count the number of functions with "q" as the suffix. */
> > +const int MATHQ_NUMS=(int)LARCH_MAX_FTYPE_MAX-(int)LARCH_BUILTIN_HUGE_VALQ;
>
> Format issue still not fixed.
>
> > +__float128 nanq (const char * str)
> > +{
> > + union _FP_UNION_Q nan;
> > + nan.bits.frac0 = 0;
> > + nan.bits.frac1 = 0;
> > + nan.bits.exp = 0x7FFF;
> > + nan.bits.sign = 1;
> > + if (str != NULL && strlen (str) > 0)
> > + return nan.flt;
> > + return 0;
> > +}
>
> I don't think the logic is correct. __builtin_nanq("") should return a
> NaN, not 0.
>
> > + if (str != NULL && strlen (str) > 0)
> > + return nan.flt;
>
> Indent is 2, not 4.
>
> And we don't need to check "str != NULL" here. Calling nan()-family
> functions with a null tagp is deemed undefined behavior.
>
> > +__float128 nansq (const char *str)
> > +{
> > + union _FP_UNION_Q nan;
> > + nan.bits.frac0 = 0;
> > + nan.bits.frac1 = 0;
> > + nan.bits.exp = 0x7FFF;
> > + nan.bits.sign = 1;
> > + if (str != NULL && strlen (str) > 0)
> > + return nan.flt;
> > + return 0;
> > +}
>
> Same logic error. And this seems exactly same as nanq, the analogous is
> definitely wrong because __builtin_nanq should return a quiet NaN, but
> __builtin_nansq should return a signaling NaN.
>
> --
> Xi Ruoyao <[email protected]>
> School of Aerospace Science and Technology, Xidian University
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