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

["Stefan Fröberg" <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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