[vlc-devel] [PATCH] configure: remove unused and broken AVX tests

[Lyndon Brown]

Please do not remove.

If you remember, I did some AVX2 work back in 2019. Due to a screw up,
only part was merged, then a portion of that reverted, and the final
fixed copy of things was never merged, being unclear whether due to
loosing interest or missing my email.

The fixed version of the work remains amongst a large block of work I'm
holding onto for later submission (re-submission in this case).

The check itself simply does not work because of a mistake fixed in the
to-be-resubmitted fixed work. I'd guessed at the correct AVX2
instruction, then forgot to go back and correct it later.

The lack of use, is simply because the block of work using it has not
yet been merged.

Once the work I did gets merged (i see no reason for it not to be), the
AVX2 check will both work and be in use.

Regards,
Lyndon

On Mon, 2020-09-14 at 20:28 +0300, Rémi Denis-Courmont wrote:
> These tests do not work in either GCC 10 or Clang 9 or earlier.
> Unsurprisingly for broken tests, nothing uses their results.
> 
> This partially reverts 629978898cf1716e3e927fb6b6a79762a5c4f0a8.
> ---
>  configure.ac | 35 -----------------------------------
>  1 file changed, 35 deletions(-)
> 
> diff --git a/configure.ac b/configure.ac
> index 99e4669942..c2443aefa8 100644
> --- a/configure.ac
> +++ b/configure.ac
> @@ -1652,41 +1652,6 @@ frobzor = (uint64_t)_mm256_extract_epi64(a,
> 0);]])], [
>    AS_IF([test "${ac_cv_c_avx2_intrinsics}" != "no"], [
>      AC_DEFINE(HAVE_AVX2_INTRINSICS, 1, [Define to 1 if AVX2
> intrinsics are available.])
>    ])
> -
> -  VLC_SAVE_FLAGS
> -  CFLAGS="${CFLAGS} -mavx"
> -  AC_CACHE_CHECK([if $CC groks AVX inline assembly],
> [ac_cv_avx_inline], [
> -    AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,[[
> -void *p;
> -asm volatile("xorps256 %%ymm1,%%ymm2"::"r"(p):"ymm1", "ymm2");
> -]])
> -    ], [
> -      ac_cv_avx_inline=yes
> -    ], [
> -      ac_cv_avx_inline=no
> -    ])
> -  ])
> -
> -  AS_IF([test "${ac_cv_avx_inline}" != "no" -a "${SYS}" !=
> "solaris"], [
> -    AC_DEFINE(CAN_COMPILE_AVX, 1, [Define to 1 if AVX inline
> assembly is available.])
> -  ])
> -
> -  AC_CACHE_CHECK([if $CC groks AVX2 inline assembly],
> [ac_cv_avx2_inline], [
> -    AC_COMPILE_IFELSE([AC_LANG_PROGRAM(,[[
> -void *p;
> -asm volatile("punpckhqdq256 %%ymm1,%%ymm2"::"r"(p):"ymm1", "ymm2");
> -]])
> -    ], [
> -      ac_cv_avx2_inline=yes
> -    ], [
> -      ac_cv_avx2_inline=no
> -    ])
> -  ])
> -  VLC_RESTORE_FLAGS
> -  AS_IF([test "${ac_cv_avx2_inline}" != "no" -a "${SYS}" !=
> "solaris"], [
> -    AC_DEFINE(CAN_COMPILE_AVX2, 1, [Define to 1 if AVX2 inline
> assembly is available.])
> -    have_avx2="yes"
> -  ])
>  ])
>  AM_CONDITIONAL([HAVE_AVX2], [test "$have_avx2" = "yes"])
>