[FFmpeg-devel] [PATCH v2] configure: Work around a start-up crash when building with clang.

[Rick Kern]

On Wed, Nov 20, 2019 at 11:29 AM Hendrik Leppkes <h.leppkes at gmail.com>
wrote:

> On Wed, Nov 20, 2019 at 5:00 PM Timo Rothenpieler <timo at rothenpieler.org>
> wrote:
> >
> > On 20.11.2019 13:51, Rick Kern wrote:
> > > The current version of clang enables stack checking by default, causing
> > > a crash when binaries are run.
> >
> > Why does it trigger a crash? Doesn't it indicate something is wrong that
> > should be fixed instead?
>

Here's the discussion about the compiler bug -
https://forums.developer.apple.com/thread/121887

Maybe this is too heavy-handed. Disabling avx, avx2, and avx512 fixes the
issue too, so maybe this is the better than disabling a security feature.
Detecting the compiler bug in configure and disabling only when present
would have less impact on performance.

I'm torn between automatically disabling it when the bug is detected, or
bailing from configure with an error message to disable it.  What's the
best option?


>
> Its a bug in the Apple compiler (not in Clang in general afaik) that
> causes stack alignment to be thrown off.
>
> The commit should probably indicate that this is a Apple compiler bug.
>
> -  Hendrik
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