[FFmpeg-devel] [PATCH 1/4] x86inc: Support arbitrary stack alignments

[Henrik Gramner]

On Mon, Aug 3, 2015 at 2:18 AM, Ronald S. Bultje <rsbultje at gmail.com> wrote:
> So, I think the code changes themselves look mostly healthy. Is there a
> behavioural difference before/after this patch? (Like: were there bugs in
> the original code, or does this change behaviour of previous code in a
> significant way?)

Should only be what's in the commit message; "Previously alignment
would occur either before or after allocating stack space depending on
whether manual alignment was required or not." which I guess you could
classify as a bug (it certainly wasn't a sensible behavior). It's the
reason for why the weird deblock stack allocation for example existed
in the first place.

So anything relying on the previous alignment behavior of automatic
stack allocation using cglobal would be affected, other than that it
shouldn't make any difference since ffmpeg doesn't use >16-byte stack
alignment.

I can only compile ffmpeg with --disable-programs when using
msys2/msvc2015 (ffmpeg.c(437): error C2039: '_cnt': is not a member of
'_iobuf'). Not sure if I'm doing something wrong, but if someone is
able to test that better that would be nice.