[FFmpeg-devel] [PATCH 2/2] Use gcc/clang builtins for av_sat_(add|sub)_64_c if available.

[Carl Eugen Hoyos]

Am Fr., 1. Mai 2020 um 20:22 Uhr schrieb James Almer <jamrial at gmail.com>:
>
> On 5/1/2020 3:07 PM, Carl Eugen Hoyos wrote:
> > Am Fr., 1. Mai 2020 um 19:24 Uhr schrieb Dale Curtis <dalecurtis at chromium.org>:
> >>
> >> Signed-off-by: Dale Curtis <dalecurtis at chromium.org>
> >> ---
> >>  libavutil/common.h | 10 ++++++++++
> >>  1 file changed, 10 insertions(+)
> >
> > Imo, this is guaranteed to break x86 compilation with some unusual
> > toolchain.
> > I looked carefully at all occurrences of AV_GCC_VERSION_AT_LEAST()
> > and I believe they are in fact different (not for x86 or combined with other
> > checks).
>
> Can you elaborate on this? AV_GCC_VERSION_AT_LEAST() is a public macro
> used in public headers to choose one or another path depending on if the
> compiler is a recent enough GCC, or something else.

> What toolchain could this break

It definitely breaks icc compilation on Linux.

> and why specifically x86?

I mentioned x86 because afaics, all existing relevant uses of
AV_GCC_VERSION_AT_LEAST() will not be triggered on x86.

Carl Eugen