[Buildroot] [PATCH] beecrypt: enable OpenMP if Buildroot GCC supports it

["Stefan Fröberg" <stefan.froberg@petroprogram.com>]

13.10.2012 17:54, Alexander Khryukin kirjoitti:
>
>
> 2012/10/13 Stefan Fr?berg <stefan.froberg@petroprogram.com
> <mailto:stefan.froberg@petroprogram.com>>
>
>     13.10.2012 16:29, Arnout Vandecappelle kirjoitti:
>>     On 13/10/12 15:25, Stefan Fr?berg wrote:
>>>     And the automatic detection didn't work for Alexander and he was
>>>     even
>>>     using the internal toolchain
>>
>>      The automatic detection did work (and it's part of autoconf,
>>     BTW).  However,
>>     beecrypt uses the OPENMP_CFLAGS given by autoconf to determine if
>>     OpenMP is
>>     available or not - but *OPENMP_CFLAGS may be empty if OpenMP is
>>     already enabled
>>     without any CFLAGS*.  So it should instead check on
>>     ac_cv_prog_c_openmp.
>>
>>      Regards,
>>      Arnout
>
>     Isn't that ac_cv_prog_c_openmp in configure file the same as
>     AC_OPENMP macro ?
>
>     And from:
>     https://www.gnu.org/software/autoconf/manual/autoconf-2.67/html_node/Generic-Compiler-Characteristics.html
>
>     /"If the current language is C, the macro //|AC_OPENMP|//sets the
>     variable //|OPENMP_CFLAGS|//to the C compiler flags needed for
>     supporting OpenMP. /*/|OPENMP_CFLAGS|/**/is set to empty if the
>     compiler already supports OpenMP, if it has no way to activate
>     OpenMP support, or if the user rejects OpenMP support by invoking
>     ?/**/configure/**/? with the ?/**/--disable-openmp/*/*? option.* //"//
>     /
>     So from that:
>     1 ) If compiler *supports* OpenMP it set's  OPENMP_CFLAGS to
>     empty. No OpenMP for you.
>     2 ) If compiler has no clue how to activate OpenMP, it will set
>     OPENMP_CFLAGS to empty. No OpenMP for you.
>     3 ) If user refuses to use OpenMP with --disable-openmp (like in
>     that my patch) it will set OPENMP_CFLAGS to empty. No OpenMP for you.
>
>
>     Quick grepping of beecrypt-4.2.1 configure file shows that   
>     OPENMP_CFLAGS=ac_cv_prog_c_openmp
>
>     grep -n ac_cv_prog_c configure
>
>     configure:17706     OPENMP_CFLAGS=$ac_cv_prog_c_openmp ;;
>
>     This all sounds soooo messy.
>
>     Regards:
>     Stefan
>
>
>
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>
>
>
> Use my patch please
>
> http://pastie.org/pastes/5052617/text
>
I would but your patch forces the use of OpenMP in beecrypt, even in
case when user's gcc does not have that for his/hers gcc.
So it will end to link error for those users.

So the beecrypt should have handled the OpenMP support by autodetecting
it (and you do have OpenMP in your gcc) in configure
process. But it did not.
And Im curious to know why.

Maybe someone could show what that mysterious AC_OPENMP actually does ...

Regards
Stefan


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