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

[James Almer]

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, and why specifically x86?
__builtin_*_overflow are arch agnostic GCC functions.

> 
> If you believe that the request for a configure check is unreasonable,
> please commit.
> 
> Carl Eugen
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