[FFmpeg-devel] [PATCH] configure: disable the new optimizer in Visual Studio 2015 Update 3

Hendrik Leppkes h.leppkes at gmail.com
Mon Jul 4 00:39:26 EEST 2016

On Tue, Jun 28, 2016 at 12:01 PM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
> On Tue, Jun 28, 2016 at 11:48 AM, Hendrik Leppkes <h.leppkes at gmail.com> wrote:
>> Visual Studio 2015 Update 3 introduced a new SSA optimizer, however
>> it unfortunately causes miscompilations. Until it is fixed, the new
>> optimizations are disabled and should be re-checked on subsequent
>> compiler releases.
>> Fixes recent FATE failure of fate-lavf-pam on VS2015.
> On that note, i'm not exactly sure which code actually miscompiles.
> I though its pamenc, but the generated files are identical, then I
> though its the crc computing code (crcenc/adler32), but those seem
> fine as well and would likely screw up in more then one case if they
> would miscompile.
> So that leaves pnmdec, I suppose, but I didn't make much headway to
> poke around in that. If anyone has any handy hints how to find the
> code in question that might be helpful.
> Maybe the code is actually not-quite-right and might enjoy some straigtening.

Applied the patch to disable the new optimizations in MSVC as I did
not spot anything obviously "bad" in pamdec - which does not mean
there isn't anything there, of course.

- Hendrik

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