Re: [Minios-devel] [UNIKRAFT/NEWLIB PATCH] include/endian.h Define the __bswap16, __bswap32, __bswap64 builtin functions only if the compilation is done with gcc

[Alice Suiu <alicesuiu17@xxxxxxxxx>]

Hi Simon,

Yes, GCC doesn't have these builtin functions, but clang has them. When I use nolibc + clang, I don't receive errors. But when I use newlib [1] + clang [2], I receive errors because both have these builtin functions.

[1] https://github.com/unikraft/lib-newlib/blob/master/include/endian.h

[2] https://clang.llvm.org/docs/LanguageExtensions.html

Thanks,

Alice

În joi, 2 apr. 2020 la 19:56, Simon Kuenzer <simon.kuenzer@xxxxxxxxx> a scris:

Hi Alice,

I have a question to this patch:

On 01.03.20 20:13, alicesuiu wrote:
> Signed-off-by: Alice Suiu <alicesuiu17@xxxxxxxxx>
> ---
>   include/endian.h | 2 ++
>   1 file changed, 2 insertions(+)
>
> diff --git a/include/endian.h b/include/endian.h
> index 3c8a752..63d3650 100644
> --- a/include/endian.h
> +++ b/include/endian.h
> @@ -41,6 +41,7 @@
>   
>   #include <stdint.h>
>   
> +#ifndef __clang__
>   static inline uint16_t __bswap16(uint16_t __x)
>   {
>       return __x<<8 | __x>>8;
> @@ -55,6 +56,7 @@ static inline uint64_t __bswap64(uint64_t __x)
>   {
>       return (__bswap32(__x)+0ULL)<<32 | __bswap32(__x>>32);
>   }
> +#endif

Doesn't GCC has a builtin for this and does clang has one, too? We also
need to make sure that clang is not introducing libc replacements as
default. On GCC that broke the printing with nolibc...

>   
>   #if __BYTE_ORDER == __LITTLE_ENDIAN
>   #define htobe16(x) __bswap16(x)
>

Thanks,

Simon

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