PATCH: Use __builtin_bswap32/64 for GCC >= 4.2

[Andreas Jaeger]

On 04/05/2012 10:08 PM, H.J. Lu wrote:
> Hi,
>
> sysdeps/x86_64/bits/byteswap.h has
>
> #if defined __GNUC__&&  __GNUC__>= 2
> ..
> #else
> # define __bswap_32(x) \
>       (__extension__
> \
>        ({ register unsigned int __x = (x); __bswap_constant_32 (__x); }))
> #endif
>
> It doesn't work for compilers without GCC __extension__
> support.
>
> This patch uses __builtin_bswap32/64 for GCC>= 4.2.
> I used inline function instead of __extension__ to avoid
> the __builtin_bswap32/64 return type issue:
>
> http://gcc.gnu.org/bugzilla/show_bug.cgi?id=37743
>
> Tested on Linux/ia32 and Linux/x86-64.  OK to install?
>
> Thanks.
>
> H.J.
> --
> 2012-04-05  H.J. Lu<hongjiu.lu@intel.com>
>
> 	* sysdeps/i386/bits/byteswap.h: (__bswap_32): Use
> 	__builtin_bswap32 for GCC>= 4.2.
> 	(__bswap_64): Use __builtin_bswap64 for GCC>= 4.2.
> 	* sysdeps/x86_64/bits/byteswap.h: Likewise.

Please check all other byteswap.h functions as well and do a similar 
change there as well.

Btw. I see a lot of duplication in this code. Perhaps we can reduce the
number of files somehow.

Andreas
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  Andreas Jaeger aj@{suse.com,opensuse.org} Twitter/Identica: jaegerandi
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