Re: [Qemu-devel] [PATCH v2 06/27] int128: Use complex numbers if advisable

[Peter Maydell]

On 1 July 2016 at 18:04, Richard Henderson <address@hidden> wrote:
> If __int128 is not supported, prefer a base type that is
> returned in registers rather than memory.

So which host architectures does this improve?
128 bit integers are nothing to do with complex numbers,
so we ought to have a strong justification for abusing
the _Complex type.

The ifdef suggests this only helps ppc and sparc, which
to my mind is not a sufficient justification.

If there's much benefit from doing this then it would be
better for the compiler on those architectures to support
int128 as a proper native type returned in registers.

> +#if defined(__GNUC__) \
> +    && (defined(__powerpc__) || defined(__sparc__)) \
> +    && !defined(CONFIG_TCG_INTERPRETER)

Why the CONFIG_TCG_INTERPRETER clause ?

thanks
-- PMM