Re: [PATCH for-6.2 1/2] include/qemu/int128.h: introduce bswap128s
On 17/08/2021 09:15, Peter Maydell wrote:
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On Tue, 17 Aug 2021 at 13:09, Matheus K. Ferst
wrote:
On 17/08/2021 06:27, Philippe Mathieu-Daudé wrote:
On 8/16/21 9:13 PM, matheus.fe...@eldorado.org.br wrote:
From: Matheus Ferst
-static inline Int128 bswap128(Int128 a)
-{
-return int128_make128(bswap64(int128_gethi(a)), bswap64(int128_getlo(a)));
-}
Personally I'd move this one to the other #ifdef side,
and implement here with __builtin_bswap128().
I saw this builtin, but I couldn't test it on my system. It seems that
Clang doesn't implement it, and it's only available on GCC 11:
https://godbolt.org/z/T6vhd5a38 . I think we can use it, but I'd need to
figure how to add a test for it in the configure script.
You should be able to get away without a configure script test --
#if __has_builtin(__builtin_bswap128)
/* version with the builtin here */
#else
/* fallback */
#endif
ought to work. (Any gcc new enough to have the builtin also has
__has_builtin; clang has had __has_builtin for ages; our compiler.h
defines a fallback "always 0" __has_builtin for older compilers.)
-- PMM
Nice, I'll prepare a v2.
--
Matheus K. Ferst
Instituto de Pesquisas ELDORADO
Re: [PATCH for-6.2 1/2] include/qemu/int128.h: introduce bswap128s
On Tue, 17 Aug 2021 at 13:09, Matheus K. Ferst
wrote:
>
> On 17/08/2021 06:27, Philippe Mathieu-Daudé wrote:
> > On 8/16/21 9:13 PM, matheus.fe...@eldorado.org.br wrote:
> >> From: Matheus Ferst
> >> -static inline Int128 bswap128(Int128 a)
> >> -{
> >> -return int128_make128(bswap64(int128_gethi(a)),
> >> bswap64(int128_getlo(a)));
> >> -}
> >
> > Personally I'd move this one to the other #ifdef side,
> > and implement here with __builtin_bswap128().
> >
>
> I saw this builtin, but I couldn't test it on my system. It seems that
> Clang doesn't implement it, and it's only available on GCC 11:
> https://godbolt.org/z/T6vhd5a38 . I think we can use it, but I'd need to
> figure how to add a test for it in the configure script.
You should be able to get away without a configure script test --
#if __has_builtin(__builtin_bswap128)
/* version with the builtin here */
#else
/* fallback */
#endif
ought to work. (Any gcc new enough to have the builtin also has
__has_builtin; clang has had __has_builtin for ages; our compiler.h
defines a fallback "always 0" __has_builtin for older compilers.)
-- PMM
Re: [PATCH for-6.2 1/2] include/qemu/int128.h: introduce bswap128s
On 17/08/2021 06:27, Philippe Mathieu-Daudé wrote:
[E-MAIL EXTERNO] Não clique em links ou abra anexos, a menos que você possa
confirmar o remetente e saber que o conteúdo é seguro. Em caso de e-mail
suspeito entre imediatamente em contato com o DTI.
On 8/16/21 9:13 PM, matheus.fe...@eldorado.org.br wrote:
From: Matheus Ferst
Introduces bswap128s based on bswap128. Since bswap128 is defined using
int128_* methods available in either CONFIG_INT128 or !CONFIG_INT128
builds, place both outside of #ifdef CONFIG_INT128.
Signed-off-by: Matheus Ferst
---
include/qemu/int128.h | 16 +++-
1 file changed, 11 insertions(+), 5 deletions(-)
diff --git a/include/qemu/int128.h b/include/qemu/int128.h
index 64500385e3..e0d385628c 100644
--- a/include/qemu/int128.h
+++ b/include/qemu/int128.h
@@ -153,11 +153,6 @@ static inline void int128_subfrom(Int128 *a, Int128 b)
*a -= b;
}
-static inline Int128 bswap128(Int128 a)
-{
-return int128_make128(bswap64(int128_gethi(a)), bswap64(int128_getlo(a)));
-}
Personally I'd move this one to the other #ifdef side,
and implement here with __builtin_bswap128().
I saw this builtin, but I couldn't test it on my system. It seems that
Clang doesn't implement it, and it's only available on GCC 11:
https://godbolt.org/z/T6vhd5a38 . I think we can use it, but I'd need to
figure how to add a test for it in the configure script.
#else /* !CONFIG_INT128 */
typedef struct Int128 Int128;
@@ -338,4 +333,15 @@ static inline void int128_subfrom(Int128 *a, Int128 b)
}
+static inline Int128 bswap128(Int128 a)
+{
+return int128_make128(bswap64(int128_gethi(a)), bswap64(int128_getlo(a)));
+}
#endif /* CONFIG_INT128 */
And add this generic one here indeed:
+static inline void bswap128s(Int128 *s)
+{
+*s = bswap128(*s);
+}
+
#endif /* INT128_H */
--
Matheus K. Ferst
Instituto de Pesquisas ELDORADO
Re: [PATCH for-6.2 1/2] include/qemu/int128.h: introduce bswap128s
On 8/16/21 9:13 PM, matheus.fe...@eldorado.org.br wrote:
> From: Matheus Ferst
>
> Introduces bswap128s based on bswap128. Since bswap128 is defined using
> int128_* methods available in either CONFIG_INT128 or !CONFIG_INT128
> builds, place both outside of #ifdef CONFIG_INT128.
>
> Signed-off-by: Matheus Ferst
> ---
> include/qemu/int128.h | 16 +++-
> 1 file changed, 11 insertions(+), 5 deletions(-)
>
> diff --git a/include/qemu/int128.h b/include/qemu/int128.h
> index 64500385e3..e0d385628c 100644
> --- a/include/qemu/int128.h
> +++ b/include/qemu/int128.h
> @@ -153,11 +153,6 @@ static inline void int128_subfrom(Int128 *a, Int128 b)
> *a -= b;
> }
>
> -static inline Int128 bswap128(Int128 a)
> -{
> -return int128_make128(bswap64(int128_gethi(a)),
> bswap64(int128_getlo(a)));
> -}
Personally I'd move this one to the other #ifdef side,
and implement here with __builtin_bswap128().
> #else /* !CONFIG_INT128 */
>
> typedef struct Int128 Int128;
> @@ -338,4 +333,15 @@ static inline void int128_subfrom(Int128 *a, Int128 b)
> }
> +static inline Int128 bswap128(Int128 a)
> +{
> +return int128_make128(bswap64(int128_gethi(a)),
> bswap64(int128_getlo(a)));
> +}
#endif /* CONFIG_INT128 */
And add this generic one here indeed:
> +static inline void bswap128s(Int128 *s)
> +{
> +*s = bswap128(*s);
> +}
> +
> #endif /* INT128_H */
>
