[FFmpeg-trac] #272(avcodec:new): altivec specific code segfaults on ppc when compiled with --enable-pic

FFmpeg trac at avcodec.org
Wed Jun 8 21:06:42 CEST 2011

#272: altivec specific code segfaults on ppc when compiled with --enable-pic
 Reporter:  kim       |        Type:  defect
   Status:  new       |    Priority:  normal
Component:  avcodec   |     Version:  unspecified
 Keywords:  ppc, PIC  |  Blocked By:
 Blocking:            |  Reproduced:  0
 Analyzed:  0         |
 When compiled with --enable-pic, ffplay segfault when using code in
 libavcodec/ppc/fft_altivec_s.S on various files. For instance when
 decoding aac or ac3 audio streams. This is always reproducible and do not
 happen when disabling pic (the default):

 Tested with latest git (47d2ca3205b53665328fe301879c339449db7a1d) but this
 has been the case for a long time I believe, I started remarking this when
 upgrading from mythtv 0.23 to 0.24, several months ago.

 from master:
 ./configure --enable-pic
 gdb ./ffplay_g ~myth/aac.dump

 Program received signal SIGSEGV, Segmentation fault.
 [Switching to Thread 0x493b5460 (LWP 32531)]
 0x10361e3c in ff_fft_calc_altivec () at libavcodec/ppc/fft_altivec_s.S:447
 447     DECL_FFTS 0

 Full gdb output attached (with bt, disass and register dump) attached.
 I believe the cause of the crash to be the loading of a global symbol in a
 non pic compatible way.

 Just doing ./configure and make, the file plays normally.

Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/272>
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