Re: [PATCH 25/72] softfloat: Rearrange FloatParts64

[Richard Henderson]

On 5/11/21 8:57 AM, Alex Bennée wrote:
> > +    union {
> > +        /* Routines that know the structure may reference the singular name. */
> > +        uint64_t frac;
> > +        /*
> > +         * Routines expanded with multiple structures reference "hi" and "lo".
> > +         * In this structure, the one word is both highest and lowest.
> > +         */
> > +        uint64_t frac_hi;
> > +        uint64_t frac_lo;
>
> This confuses me. Is this because it could be frac_hi or frac_lo at the
> "top" of the structure because of endian issues?

Nothing about endianness.  There is exactly one element, so it is both the 
"first" and "last", both "high" and "low".

Generic code will examine the "high" word when looking at overflow and things 
related, and the "low" word when doing rounding.

This anonymous union gives the same element 3 different names.

r~