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 - # version check once its fixed - check_cflags -d2SSAOptimizer- + # Issue has been fixed in MSVC v19.00.24218. + check_cpp_condition windows.h "_MSC_FULL_VER >= 190024218" || + check_cflags -d2SSAOptimizer- fi for pfx in "" host_; do -- 2.10.0.windows.1.325.ge6089c1 - Kacper _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
