[FFmpeg-trac] #7788(avcodec:new): Custom-compiled FFmpeg 4.1.1 crashes on MacOS when reading files
FFmpeg
trac at avcodec.org
Tue Mar 12 19:02:06 EET 2019
#7788: Custom-compiled FFmpeg 4.1.1 crashes on MacOS when reading files
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Reporter: Jim_ChamSys | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: 4.1 | Resolution:
Keywords: | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by jamrial):
>I compiled with --enable-debug=gdb and --disable-optimizations (on top of
the previously used flags), and the crash wouldn't happen
>rbx = 0x000000010302e8c8
>-> 0x1009dbd72 <+134>: movdqa %xmm0, (%rbx)
Looks like a compiler bug. The code it generates results in unaligned
memory access when using movdqa, something that doesn't happen when you
compile with --disable-optimizations as it removes -O3 and similar
compiler optimization flags.
Is this the same compiler you used for ffmpeg 3.4.2, which you say worked?
It's evidently ignoring the -fno-tree-vectorize flag we use precisely to
prevent compilers from making mistakes like this.
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Ticket URL: <https://trac.ffmpeg.org/ticket/7788#comment:4>
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