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

[Rémi Denis-Courmont]

Le maanantaina 14. syyskuuta 2020, 23.08.34 EEST Francois Cartegnie a écrit :
> Le 14/09/2020 à 20:21, Rémi Denis-Courmont a écrit :
> > Le maanantaina 14. syyskuuta 2020, 20.34.12 EEST Francois Cartegnie a 
écrit :
> >> Le 14/09/2020 à 19:28, Rémi Denis-Courmont a écrit :
> >>> These tests do not work in either GCC 10 or Clang 9 or earlier.
> >>> Unsurprisingly for broken tests, nothing uses their results.
> >> 
> >> Because they are removed, seen as no-op ?
> > 
> > No, literally nothing uses CAN_COMPILE_AVX.
> > In fact, I forgot to remove HAVE_AVX2.
> > 
> > (HAVE_AVX2_INSTRINSICS is unused, but at least it gets provisoned
> > correctly.)

> I meant: the tests are failing because the compiler sees it as no-op (no
> output constraint or artificial dependency).

Absolutely not. Because the asm blocks are volatile, they will be evaluated 
for side effects even if they have no reverse dependencies.

In this case, the tests are failing because the assembler does not accept the 
syntax. This is clear from config.log.

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