Re: [PATCH v3 1/5] LoongArch: Fix usage of LSX and LASX frint/ftint instructions [PR112578]

[Xi Ruoyao <xry111@xry111.site>]

On Fri, 2023-11-24 at 16:01 +0800, chenglulu wrote:
> I only saw lrint llrint in n2310 with this description:
> 
> F7.12.9.5
> 
> "The lrint and llrint functions round their argument to the nearest 
> integer value, rounding
> according to the current rounding direction. If the rounded value is 
> outside the range of the return
> type, the numeric result is unspecified and a domain error or range 
> error may occur."
> 
> I don't know if I'm right?

There's an explanation in the linux man-page for lrint:

       SUSv2 and POSIX.1‐2001 contain text about overflow (which might set er‐
       rno to ERANGE, or raise an FE_OVERFLOW exception).   In  practice,  the
       result  cannot  overflow on any current machine, so this error‐handling
       stuff is just nonsense.  (More precisely, overflow can happen only when
       the maximum value of the exponent is smaller than the  number  of  man‐
       tissa bits.  For the IEEE‐754 standard 32‐bit and 64‐bit floating‐point
       numbers  the maximum value of the exponent is 127 (respectively, 1023),
       and the number of mantissa bits including the implicit bit is  24  (re‐
       spectively, 53).)

-- 
Xi Ruoyao <xry111@xry111.site>
School of Aerospace Science and Technology, Xidian University