[FFmpeg-trac] #7665(avutil:new): DJGPP: alignment silently reduced to 16 bytes with questionable reason

FFmpeg trac at avcodec.org
Thu Jan 10 19:26:27 EET 2019


#7665: DJGPP: alignment silently reduced to 16 bytes with questionable reason
-------------------------------------+-------------------------------------
             Reporter:               |                     Type:  defect
  michael.kostylev                   |                 Priority:  normal
               Status:  new          |                  Version:  git-
            Component:  avutil       |  master
             Keywords:               |               Blocked By:
             Blocking:               |  Reproduced by developer:  0
Analyzed by developer:  0            |
-------------------------------------+-------------------------------------
 Summary of the bug:

 Commit 1473afac5d11a0a90810b6cd8107d63640c9fd38 actually broke the
 AVX code when the compiler is able to build it. The vast majority of the
 DJGPP toolchains are unable to maintain even the 16-byte alingment, so the
 only good workaround for such a toolchain is to use --disable-sse. That in
 turn could be a  a good reason for relaxing alignment requirements.

 How to reproduce:
 {{{
 See http://fate.xffm.org/report.cgi?slot=x86_32-freedos-
 gcc-4.8-avx2&time=20190105220055
 The code 255 (SIGSEGV, actually) is caused by reduced alignment, the rest
 looks as dosemu-related.
 }}}

--
Ticket URL: <https://trac.ffmpeg.org/ticket/7665>
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