On Fri, Jan 06, 2017 at 12:11:57AM +0100, Kacper Michajlow wrote: > 2016-07-04 3:53 GMT+02:00 Kacper Michajlow <kaspe...@gmail.com>: > > 2016-07-03 23:39 GMT+02:00 Hendrik Leppkes <h.lepp...@gmail.com>: > >> On Tue, Jun 28, 2016 at 12:01 PM, Hendrik Leppkes <h.lepp...@gmail.com> > >> wrote: > >>> On Tue, Jun 28, 2016 at 11:48 AM, Hendrik Leppkes <h.lepp...@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. > >> > > > > This is pretty bad miscompilation in new SSA optimizer. It assumes > > that variable declared in loop doesn't change the value even if there > > is assignment. I minimized testcese and reported the bug > > https://connect.microsoft.com/VisualStudio/feedback/details/2890170 > > > > - Kacper > > Sorry for bumping such old thread, but I just got information that the > bug has been fixed in MSVC. > > It is fixed in hotfix for VS2015 - KB3207317 > https://support.microsoft.com/en-us/kb/3207317 and of course in > upcoming VS2017. > > I've confirmed that this hotfix fixes fate-lavf-pam test. The > following change will enable SSA Optimizer on newer compiler versions. > > --- > configure | 6 +++--- > 1 file changed, 3 insertions(+), 3 deletions(-) > > diff --git a/configure b/configure > index 398e843..cf82b3b 100755 > --- a/configure > +++ b/configure > @@ -6317,9 +6317,9 @@ EOF > check_func strtoll || add_cflags -Dstrtoll=_strtoi64 > check_func strtoull || add_cflags -Dstrtoull=_strtoui64 > # the new SSA optimzer in VS2015 U3 is mis-optimizing some parts > of the code > - # this flag should be re-checked on newer compiler releases and put > under a
patch is currupted by stray newline [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Its not that you shouldnt use gotos but rather that you should write readable code and code with gotos often but not always is less readable
signature.asc
Description: Digital signature
_______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
