[Pixman] [PATCH] [v3] test: add a check for FE_DIVBYZERO

[Siarhei Siamashka]

On Thu, 17 Sep 2015 15:43:27 +0200
Marek Vasut <marex at denx.de> wrote:

> From: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> 
> Some architectures, such as Microblaze and Nios2, currently do not
> implement FE_DIVBYZERO, even though they have <fenv.h> and
> feenableexcept(). This commit adds a configure.ac check to verify
> whether FE_DIVBYZERO is defined or not, and if not, disables the
> problematic code in test/utils.c.
> 
> Signed-off-by: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Signed-off-by: Marek Vasut <marex at denx.de>
> 
> ---
> Changes v1 -> v2:
> 
>  * Use the ac_cv_have_decl_FE_DIVBYZERO variable, which is
>    automatically set by AC_CHECK_DECL, to decide whether or not
>    HAVE_FEDIVBYZERO should be defined.
> 
> Changes v2 -> v3:
> 
>  * Use action-if-yes of AC_CHECK_DECL as suggested in
>    http://lists.freedesktop.org/archives/pixman/2014-February/003176.html
> ---
>  configure.ac | 5 +++++
>  test/utils.c | 2 ++
>  2 files changed, 7 insertions(+)
> 
> diff --git a/configure.ac b/configure.ac
> index f93cc30..424bfd3 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -891,6 +891,11 @@ if test x$have_feenableexcept = xyes; then
>     AC_DEFINE(HAVE_FEENABLEEXCEPT, 1, [Whether we have feenableexcept()])
>  fi
>  
> +AC_CHECK_DECL([FE_DIVBYZERO],
> +	[AC_DEFINE(HAVE_FEDIVBYZERO, 1, [Whether we have FE_DIVBYZERO])],
> +	[],
> +	[[#include <fenv.h>]])
> +
>  AC_CHECK_FUNC(gettimeofday, have_gettimeofday=yes, have_gettimeofday=no)
>  AC_CHECK_HEADER(sys/time.h, have_sys_time_h=yes, have_sys_time_h=no)
>  if test x$have_gettimeofday = xyes && test x$have_sys_time_h = xyes; then
> diff --git a/test/utils.c b/test/utils.c
> index 222d4d5..8657966 100644
> --- a/test/utils.c
> +++ b/test/utils.c
> @@ -966,9 +966,11 @@ enable_divbyzero_exceptions (void)
>  {
>  #ifdef HAVE_FENV_H
>  #ifdef HAVE_FEENABLEEXCEPT
> +#ifdef HAVE_FEDIVBYZERO
>      feenableexcept (FE_DIVBYZERO);
> +#endif
>  #endif
>  #endif
>  }
>  
>  void

Thanks for the patch:
Acked-by: Siarhei Siamashka <siarhei.siamashka at gmail.com>

If it is not a big secret, how is pixman used on these Microblaze
and Nios2 architectures in practice? Is it doing any performance
critical job? We obviously don't have any assembly optimizations for
Microblaze and Nios2 yet. As for the generic C code in pixman, it
could be improved in some places too.

Also just in case, does pixman successfully pass the "make check"
test on these architectures? In practice, it is more of a stress for
the C compiler than for the pixman code itself. Running this test on
real hardware can be very slow, so it may be preferable to run it in
QEMU (thus testing QEMU too). I had an old wiki page describing how
to do this for MIPS:
    https://github.com/ssvb/QEMU/wiki/MIPS
Running the full pixman test suite used to take more than 30 hours
on my Asus RT N16 router (MIPS74K 480MHz) the last time I checked it.
It was so slow primarily because of the missing FPU, and I had floating
point instructions trapped and emulated by the kernel (the rootfs was
not softfloat). The time is reduced to only half an hour when the
pixman test suite is run emulated by QEMU on my Intel Core i7 desktop
machine :-)

-- 
Best regards,
Siarhei Siamashka