https://bugs.kde.org/show_bug.cgi?id=378627
Bug ID: 378627
Summary: False positive with GCC 6.3.1 and -fno-ipa-cp-clone
(-O3)
Product: valgrind
Version: unspecified
Platform: Other
OS: Linux
Status: UNCONFIRMED
Severity: normal
Priority: NOR
Component: memcheck
Assignee: [email protected]
Reporter: [email protected]
Target Milestone: ---
In FFmpeg we have the following false-report reported by valgrind memcheck:
==28424== Memcheck, a memory error detector
==28424== Copyright (C) 2002-2015, and GNU GPL'd, by Julian Seward et al.
==28424== Using Valgrind-3.13.0.SVN and LibVEX; rerun with -h for copyright
info
==28424== Command: ./ffmpeg_g -f lavfi -i testsrc -frames:v 1 -c ffv1 -f null -
==28424==
ffmpeg version N-85447-g8839cbf911 Copyright (c) 2000-2017 the FFmpeg
developers
built with gcc 6.3.1 (GCC) 20170306
configuration: --enable-gpl --enable-libx264 --enable-libass
--enable-libfreetype --enable-fontconfig --assert-level=2
--samples=/home/ux/fate-samples --enable-libdc1394 --enable-libvpx
libavutil 55. 60.101 / 55. 60.101
libavcodec 57. 92.100 / 57. 92.100
libavformat 57. 72.100 / 57. 72.100
libavdevice 57. 7.100 / 57. 7.100
libavfilter 6. 84.101 / 6. 84.101
libswscale 4. 7.100 / 4. 7.100
libswresample 2. 8.100 / 2. 8.100
libpostproc 54. 6.100 / 54. 6.100
Input #0, lavfi, from 'testsrc':
Duration: N/A, start: 0.000000, bitrate: N/A
Stream #0:0: Video: rawvideo (RGB[24] / 0x18424752), rgb24, 320x240 [SAR
1:1 DAR 4:3], 25 tbr, 25 tbn, 25 tbc
Stream mapping:
Stream #0:0 -> #0:0 (rawvideo (native) -> ffv1 (native))
Press [q] to stop, [?] for help
Output #0, null, to 'pipe:':
Metadata:
encoder : Lavf57.72.100
Stream #0:0: Video: ffv1, bgr0, 320x240 [SAR 1:1 DAR 4:3], q=2-31, 200
kb/s, 25 fps, 25 tbn, 25 tbc
Metadata:
encoder : Lavc57.92.100 ffv1
==28424== Thread 21:
==28424== Conditional jump or move depends on uninitialised value(s)
==28424== at 0x81196B: encode_line (ffv1enc_template.c:58)
==28424== by 0x81196B: encode_rgb_frame (ffv1enc_template.c:187)
==28424== by 0x815B34: encode_slice (ffv1enc.c:1067)
==28424== by 0xA069BA: worker (pthread_slice.c:93)
==28424== by 0x8C1E2E6: start_thread (in /usr/lib/libpthread-2.25.so)
==28424== by 0x8F2154E: clone (in /usr/lib/libc-2.25.so)
==28424==
frame= 1 fps=0.0 q=-0.0 Lsize=N/A time=00:00:00.04 bitrate=N/A speed=0.13x
video:4kB audio:0kB subtitle:0kB other streams:0kB global headers:0kB muxing
overhead: unknown
==28424==
==28424== HEAP SUMMARY:
==28424== in use at exit: 18,644 bytes in 7 blocks
==28424== total heap usage: 2,642 allocs, 2,635 frees, 14,334,780 bytes
allocated
==28424==
==28424== LEAK SUMMARY:
==28424== definitely lost: 0 bytes in 0 blocks
==28424== indirectly lost: 0 bytes in 0 blocks
==28424== possibly lost: 0 bytes in 0 blocks
==28424== still reachable: 18,644 bytes in 7 blocks
==28424== suppressed: 0 bytes in 0 blocks
==28424== Rerun with --leak-check=full to see details of leaked memory
==28424==
==28424== For counts of detected and suppressed errors, rerun with: -v
==28424== Use --track-origins=yes to see where uninitialised values come from
==28424== ERROR SUMMARY: 230400 errors from 1 contexts (suppressed: 0 from 0)
Both valgrind stable (3.12.0) and current SVN (r16297, VEX r3344) are affected.
I don't know if it's a regression.
This is not reproducible when using -fno-ipa-cp-clone or with clang.
The source code can be found in libavcodec/ffv1enc_template.c
(http://git.videolan.org/?p=ffmpeg.git;a=blob;f=libavcodec/ffv1enc_template.c;hb=HEAD).
No sample are required to reproduce (see the testsrc command used in the log
above).
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