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

James Almer jamrial at gmail.com
Mon Aug 3 17:26:06 CEST 2015

On 03/08/15 9:50 AM, Hendrik Leppkes wrote:
> On Mon, Aug 3, 2015 at 10:31 AM, Henrik Gramner <henrik at gramner.com> wrote:
>> 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.
> msvc2015 support is unfortunately still broken. I'll send a patch
> later for this.
> Otherwise, I tested the patch with msvc 2013 32-bit, and fate passed fine.
> If there is something else I should specifically test which may not be
> covered by fate, let me know.

Just to be sure try to convert an 8ch audio stream from float/s24 to floatp/s24p.
See if it crashes or gives wrong output.

> - Hendrik
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