ffmpeg/libavcodec/x86
yang 6a2bad2c4f dsputil_mmx: fix incorrect assembly code
In file libavcodec/x86/dsputil_mmx.c, function ff_put_pixels_clamped_mmx(), there are two assembly code blocks. In the first block (in the unrolled loop), the instructions "movq 8%3, %%mm1 \n\t" etc have problem.
For above instruction, it is clear what the programmer wants: a load from p + 8. But this assembly code doesn’t guarantee that. It only works if the compiler puts p in a register to produce an instruction like this: “movq 8(%edi), %mm1”. During compiler optimization, it is possible that the compiler will be able to constant propagate into p. Suppose p = &x[10000]. Then operand 3 can become 10000(%edi), where %edi holds &x. And the instruction becomes “movq 810000(%edx)”. That is, it will stride by 810000 instead of 8.
This will cause the segmentation fault.
This error was fixed in the second block of the assembly code, but not in the unrolled loop.

How to reproduce:
This error is exposed when we build the ffmpeg using Intel C++ Compiler, IPO+PGO optimization. The ffmpeg was crashed when decoding a mjpeg video.

Signed-off-by: Michael Niedermayer <michaelni@gmx.at>
2012-07-24 00:55:05 +02:00
..
ac3dsp_mmx.c
ac3dsp.asm
cabac.h
cavsdsp_mmx.c
dct32_sse.asm
deinterlace.asm
diracdsp_mmx.c
diracdsp_mmx.h
diracdsp_yasm.asm
dnxhd_mmx.c
dsputil_mmx_avg_template.c
dsputil_mmx_qns_template.c
dsputil_mmx_rnd_template.c
dsputil_mmx.c dsputil_mmx: fix incorrect assembly code 2012-07-24 00:55:05 +02:00
dsputil_mmx.h
dsputil_yasm.asm Merge remote-tracking branch 'qatar/master' 2012-07-23 21:25:09 +02:00
dsputilenc_mmx.c
dsputilenc_yasm.asm
dwt_yasm.asm
dwt.c
dwt.h
fdct_mmx.c
fft_3dn2.c
fft_3dn.c
fft_mmx.asm
fft.c
fft.h
fmtconvert_mmx.c
fmtconvert.asm
h264_chromamc_10bit.asm
h264_chromamc.asm
h264_deblock_10bit.asm
h264_deblock.asm
h264_i386.h
h264_idct_10bit.asm
h264_idct.asm
h264_intrapred_10bit.asm
h264_intrapred_init.c Merge remote-tracking branch 'qatar/master' 2012-07-05 21:55:31 +02:00
h264_intrapred.asm Merge remote-tracking branch 'qatar/master' 2012-07-07 20:29:43 +02:00
h264_qpel_10bit.asm
h264_qpel_mmx.c
h264_weight_10bit.asm
h264_weight.asm
h264dsp_mmx.c
idct_mmx_xvid.c
idct_mmx.c
idct_sse2_xvid.c
idct_xvid.h
imdct36_sse.asm
lpc_mmx.c
Makefile Merge remote-tracking branch 'qatar/master' 2012-07-18 22:34:48 +02:00
mathops.h
mlpdsp.c
motion_est_mmx.c
mpegaudiodec_mmx.c
mpegvideo_mmx_template.c
mpegvideo_mmx.c
pngdsp-init.c
pngdsp.asm
proresdsp-init.c
proresdsp.asm
rv34dsp_init.c
rv34dsp.asm
rv40dsp_init.c
rv40dsp.asm
sbrdsp_init.c
sbrdsp.asm
simple_idct_mmx.c
snowdsp_mmx.c
v210-init.c
v210.asm
vc1dsp_mmx.c
vc1dsp_yasm.asm
vp3dsp_init.c Merge remote-tracking branch 'qatar/master' 2012-07-18 22:34:48 +02:00
vp3dsp.asm Merge remote-tracking branch 'qatar/master' 2012-07-18 22:34:48 +02:00
vp8dsp-init.c Merge remote-tracking branch 'qatar/master' 2012-07-05 21:55:31 +02:00
vp8dsp.asm Merge remote-tracking branch 'qatar/master' 2012-07-05 21:55:31 +02:00
vp56_arith.h
vp56dsp_init.c
vp56dsp.asm
w64xmmtest.c