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

[Paolo Bonzini]

On 01/07/2016 19:04, Richard Henderson wrote:
> If __int128 is not supported, prefer a base type that is
> returned in registers rather than memory.
> 
> Signed-off-by: Richard Henderson <address@hidden>
> ---
>  include/qemu/int128.h | 110 
> +++++++++++++++++++++++++++++++-------------------
>  1 file changed, 69 insertions(+), 41 deletions(-)
> 
> diff --git a/include/qemu/int128.h b/include/qemu/int128.h
> index 67440fa..ab67275 100644
> --- a/include/qemu/int128.h
> +++ b/include/qemu/int128.h
> @@ -139,27 +139,37 @@ static inline void int128_subfrom(Int128 *a, Int128 b)
>  
>  #else /* !CONFIG_INT128 */
>  
> -typedef struct Int128 Int128;
> +/* Here we are catering to the ABI of the host.  If the host returns
> +   64-bit complex in registers, but the 128-bit structure in memory,
> +   then choose the complex representation.  */
> +#if defined(__GNUC__) \
> +    && (defined(__powerpc__) || defined(__sparc__)) \
> +    && !defined(CONFIG_TCG_INTERPRETER)
> +typedef _Complex unsigned long long Int128;

Is there any reason not to do that unconditionally?

Paolo